PHILADELPHIA (CBS) -- Philadelphia police are investigating a brutal beating and sexual assault in a Center City office building.
"He's a violent sexual predator, make no doubt about it," Philadelphia Police Capt. James Kearney said.
And he's still on the run.
Philadelphia police say at about 2:15 p.m. Tuesday a man entered an office building near 13th and Race Streets. He then went to a law office on the eighth floor, where he encountered a 22-year-old office worker.
Police say he initially asked her for someone who didn't work there. He then turned violent.
"The male became frustrated and angry," Kearney said. "Beat our female and proceeded to choke her, punch her. When she tried to get up or scream, he would choke and punch her again and then, he sexually assaulted and raped her."
It's not clear how the man got into the building. Eyewitness News' cameras captured people having to get buzzed inside. There's also signage and cameras on the exterior of the building.
After the attack, police say those cameras captured the man running east on Spring Street. But he then disappeared from the camera's view for 20 minutes. He later reemerged going north on 12th Street.
"Our witness and our victim describe the male as being in his 30s between the 5-8 and 5-11, regular build, dark-complected," Kearney said.
He was last seen wearing a black baseball cap, a black T-shirt and blue jeans with a black and silver belt.
Police say he has not been linked to other assaults.
Investigators also say he is not known to the victim.
But moments before Tuesday's assault, he was spotted outside of the building.
"We want everybody to be vigilant. Be aware of your surroundings," Kearney said. "These people are out there. There are predators out there."
While police are asking for your help in identifying the suspect, they say do not approach him. Instead, call 911.
CBS3's Wakisha Bailey reports.
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