10:23 AM PT -- Law enforcement sources tell TMZ the man who breached the White House fence Friday had not been on the Secret Service's radar, and had no criminal history.
A man wearing a backpack was arrested by the Secret Service after he breached the White House fence late Friday night ... while Donald Trump was inside the building.
The man was discovered by a Secret Service agent just before midnight by the south entrance of the White House, and was promptly taken into custody.
No hazardous materials were found in his backpack, and a search on the grounds yielded no further signs of danger.
Trump, who was home at the time, was notified of the breach ... prompting the White House to be placed under extremely tight security.
This marks the 1st time someone has tried breaking onto the White House grounds since Trump has taken office. Obama had a handful of security breaches himself.