Nurse!

The footage -- shot in Rochester, Minnesota at Whiskey Bones Road House -- shows Gallagher slam something with his sledgehammer ... then hunch over and fall backwards onto the stage.

Moments after Gallagher hits the ground, people from the audience ran on stage to help. He was transported to Saint Mary's Hospital shortly after the incident.

A rep for Gallagher tells TMZ he is awake this morning, feeling weak, but his spirits are good. Doctors have not yet determined what happened.

UPDATE: Gallagher's manager tells TMZ he will cancel his next few shows, scheduled for tonight and tomorrow, and the rest of his upcoming schedule is up in the air ... depending on how he checks out. There is no timetable for his release.

Multiple witnesses tell TMZ Gallagher was doing his famous sledge-o-matic routine when he fell backwards onto the stage. We're told his eyes were closed and he was shaking.

Doctors -- who happened to be in the audience -- rushed on stage and straightened out Gallagher's arms ... and waited by his side until the ambulance arrived.

According to Yankees General Manager Brian Cashman, Yogi -- who works as an "instructor" for the Yanks -- caught his foot on a carpet at Bright House Field in Florida. Though he didn't hit his head, Yogi was taken to a nearby hospital was for precautionary reasons.

In fact, Cashman claims Yogi was smiling and joking after the accident ... and didn't even want medical attention.

***WARNING -- GRAPHIC FOOTAGE***

It all went down during a recent taping for "Jump City" on G4 -- featuring Parkour teams from across the country, competing against each other by maneuvering insane obstacles.

Parkour master Levi Meeuwenberg tripped over an elevated railing and plummeted head first down a 10 foot drop on to a concrete stairway. When Levi got up, his arm was pointing in all sorts of different directions.

We're told Levi had pins and metal plates surgically implanted into his arm to help reset the bone.

No word on his current condition -- but we're guessing he won't be competing any time soon.

Spectacular tweeted the pics from his hospital bed last night, saying, "Just got into a accident, and everything on my body is hurting.. And now my Lamborghini is gone :("

David was driving in West Hollywood just a few minutes ago ... when his car veered into oncoming traffic.

David is lying on the ground right now -- bleeding -- as fire trucks are racing to the scene.

A witness tells TMZ ... David was behind a car that stopped suddenly. David then swerved to the left to avoid hitting the car and went into oncoming traffic. David slammed into a car going in the opposite direction.

David was driving a silver Cadillac.

We're told David was on his way to Burbank airport to board a private jet which was going to Las Vegas, for the grand opening of Sugar Factory -- a candy store at the Paris Hotel. He was supposed to attend a party hosted by Kim Kardashian.

UPDATE: He's being taken away by ambulance right now.

UPDATE 3:13 PM PT: Authorities now say the drivers of both vehicles suffered minor to moderate injuries.

Collins claims she had a "Victorian swoon" caused by the skin-hugging dress she wore to the Vanity Fair party at the Sunset Tower Hotel

Collins told reporters, “We went to the hospital and they did all the tests before the doctors told me I was absolutely fine and released me. The truth was, I made the wrong decision to wear a very tight dress and had something rather like a Victorian swoon."

She added, “The good news is, I am in good health and feel fine today.”

Williams' rep released a statement explaining, "Monday Serena Williams underwent emergency treatment at Cedars for a hematoma she suffered as a result of treatment for a more critical situation."

The statement continues, "Last week, Serena suffered from a pulmonary embolism [a blood clot in the lungs] which was discovered upon her return to L.A. She had been in New York for doctor appointments for the ongoing issues with her foot."

TMZ obtained a police report filed in Phoenix, AZ last Friday. According to the report, Muniz and his girlfriend, Elycia Turnbow, were arguing in their home about "prior relationships." Elycia told cops, Frankie "grabbed a gun and held it to his head, possibly with the intent of committing suicide."

Elycia says she became worried and called one of Frankie's bandmates to take him to the hospital.

Frankie tells a different story, claiming Elycia was screaming and yelling at him when he "fell and hit his head." Muniz says that's why he went to the hospital. Muniz denied putting a gun to his head, but did say, "I grabbed the case, but not the gun ... it isn't even loaded."

In fact ... the cops did find the gun and it was loaded.

Muniz was released a short time later, went home, and just after 10PM the same night, things exploded back at the house. According to the police report, Elycia says, Frankie "punched her in the back of the head, and threw her into a wall while in the downstairs bedroom."

Muniz denied punching Elycia, telling cops, "I love her too much. She is the woman I want to marry."

Muniz told cops ... what actually happened was that he was sleeping but awakened "by Elycia yelling at him and hitting him in the face." Muniz said he was defending himself when "Elycia fell to the ground and started to kick the bedroom door."

Cops say in the report ... there were no visible injuries.

The handgun was impounded and both Frankie and Elycia were warned they'd both go to jail if things got out of control again.

Sources connected with "Justified" tell us the 30-year-old woman -- who suffered severe head trauma during a "low speed" collision with a vehicle -- is also regaining the ability to move on her own.

We're told the woman has begun to talk again as well.

Law enforcement sources tell us ... the 30-year-old woman was struck in a "low speed collision" and smacked her head on concrete as she fell backwards.

We're told the woman was transported to a nearby hospital for severe head trauma.

Law enforcement sources confirm ... the 60-year-old driver had some kind of medical emergency behind the wheel and veered on to the L.A. area set -- striking a 52-year-old male security guard.

We're told the security guard was transported to a nearby hospital in critical condition -- but died from his injuries a short time later.

The accident is still under investigation.

UPDATE: CBS has released a statement saying the studio is "cooperating with the local authorities in Santa Clarita to help determine what caused this terrible accident."

CBS notes production on the show has been suspended until further notice.

NCIS producers, cast and crew also released a joint statement saying, "With profound sympathy we mourn the tragic passing of our co-worker and friend."

Gabor -- who was released from the hospital hours before these photos were taken -- is still bed-ridden ... but doctors say her infection is gone and her blood pressure has stabilized.

Five of the injured were transported to local hospitals, one of them being critical. We're told the other injured person was transported by private vehicle.

A rep for the NFL tells TMZ: "The ice and snow melting off of the Cowboys Stadium roof has caused several sliding snow falls onto the plazas. There have been several injuries. All stadium entrances have been closed except for the truck tunnel, which is away from the building by a very safe distance. All workers and visitors will now enter and exit through the tunnel until further notice."

Amanpour claims, "An angry mob surrounded us and chased us into the car shouting that they hate America. They kicked in the car doors and broke our windshield as we drove away."

As we previously reported, Anderson Cooper claims he was punched in the head by members of a violent pro-Mubarak mob early this morning.