Philadelphia police and the FBI are searching for four men who sexually assaulted and robbed a woman during a home invasion in South Philadelphia today.

The victim's brother, Davey Johnson, who was present during the crime, is being treated as a victim and is missing, said Capt. John Darby of the Special Victims Unit.

Johnson, 24, is about 6-foot-1, with a thin build, a moustache and beard. He was last seen wearing an orange T-shirt and tan cargo shorts, Darby said.

The victim, 29, lives with her daughter, 12, and niece, 2, on the 2000 block of South Norwich Street. According to police, she was awakened about 4 a.m. by a call from her brother asking for money because he said he was being evicted. She said no.

Around 5:30 a.m., he called again, then appeared at her front door, police said. When she opened it, three men, including one with a silver handgun, forced Johnson and her inside the house. They were later joined by a fourth man.

They demanded her ATM card and PIN. As three of the assailants and Johnson went to three ATMs, extracting a total of $600, the fourth sexually assaulted the victim, police said.

When they returned, each of the three assailants sexually assaulted the victim, police said. Then all four left, with the victim's brother, in a red, four-door sedan, possibly a Crown Victoria or Grand Marquis, police said.

Police described the first assailant as about 21, 6-foot-1, with a teardrop tattoo under one eye. He was last seen wearing a white shirt and jeans.

The second, about 20, is 5-foot-4, with a thin build and light-colored eyes. He was wearing a black baseball cap, black shirt and tan shorts.

The third is also about 20, 5-foot-7, with a dark complexion. He was wearing a black hooded sweatshirt.

The fourth, about 20, is 5-foot-5, with a light complexion, a wide face, and cornrowed hair. He was wearing a black shirt and tan trousers.

The woman was briefly hospitalized, then released. The children slept through the attacks, police said.

Anyone with information should contact the city's tip line at 215-686-TIPS or the Special Victims Unit at 215-685-3251, 215-685-3252 or 215-685-3253.

Contact Gail Shister at gshister@phillynews.com or 215-854-2224.