Whitney Houston Death

Beverly Hills police have sealed off the room where Whitney Houston died and will not enter until they obtain a search warrant ... TMZ has learned.

Law enforcement sources tell us ... the police want to conduct a thorough search of the hotel room, but are exercising caution by getting a warrant. We're told one thing police are interested in is whether drugs are present in the room.

Although police could seize items in plain view, we're told they want a top-to-bottom search of the room.

In a statement, the group tells TMZ, "We are absolutely shocked and saddened by the sudden and untimely death of our dear sister Whitney. As a group, we are extremely close; when one of us hurts, we all hurt."

Bobby Brown, Whitney's ex-husband and father of her only child, is a member of the band.

They continue, "As much as we are in pain right now, we will continue to draw strength from God, as we support and comfort our brother Bobby, their daughter Bobbi-Christina and Whitney's mother Cissy Houston. Our thoughts and prayers remain with the entire Brown-Houston family today and always."

Clive Davis' annual pre-Grammy party is going on tonight as scheduled ... despite the death of Whitney Houston ... sources close to Davis tell TMZ.

According to our sources, while the party will go on ... Davis is not in attendance.

Our sources say Davis is currently at his home in Los Angeles. We're told he is surrounded by close friends.

Whitney Houston "partied heavily" at the Beverly Hilton hotel with a group of friends ... hotel staff tell TMZ.

We're told Whitney and her friends were in the bar for a time and the group was drinking and very loud. Our sources say even though the hotel is busy with all the Grammy festivities, Whitney and her group stood out because they were so boisterous.

Again, it's too early to know what caused her death.

Dionne Warwick and Cissy Houston spoke with Whitney Houston by phone just before she died and say Whitney seemed fine ... TMZ has learned.

Whitney's mother, Cissy Houston, spoke with her daughter 25-30 minutes before she died and nothing seemed unusual ... sources tell TMZ. We're told they talked about attending the Clive Davis pre-Grammy party.

Dionne Warwick, Whitney's cousin, called as well ... several hours before Whitney died ... to make sure they were sitting at the same table at Clive's party. And again ... there were no signs of trouble.

The people in touch with Dionne say she is inconsolable adding, "She is an absolute mess."

Bobby Brown is distraught and "in and out of crying fits" ... after getting the news that Whitney Houston is dead -- but his New Edition band mates are by his side trying to console him.

New Edition has a concert tonight in Mississippi -- and believe it or not sources close to the group tell TMZ ... not only will New Edition go on as scheduled, but as of now Bobby is also planning to perform.

We're told Bobby is going to try to get through the entire show.

Bobby and Whitney had an infamously tumultuous 15 year marriage.