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

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

Johnson, 24, is about 6 feet, 1 inch tall, with a thin build, a mustache and a 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. 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.

About 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 her PIN. As three of the assailants and Johnson went to three ATM machines, 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 Ford Crown Victoria or Mercury 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, a 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, 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. The children slept through the attacks, police said.

Anyone with information is asked to call the city tip line, 215-686-8477 (215-686-TIPS), or the SVU at 215-685-3251, -52 or -53.