— -- The hunt is on for suspected gang members who may be responsible for the random killing of a pregant woman trick or treating with her three small children Wedneasday night.

Leticia Barrera, 38 years old and seven months pregnant, was accompanying her children, ages 3, 5 and 7, when she was struck in the head by what police believe was likely a random bullet. The children were not hurt in the shooting.

"All I heard was four gunshots," Anna Rega, a witness to the crime, told ABC News' local affiliate. "Then I called the cops. I called the police on my cell phone. I told them there was shooting. And then everybody just started coming."

Police told the affiliate they are searching for two young men wearing hooded sweatshirts. The men, possibly in their teens, may have been targeting rival gang members when the stray bullet hit.

Barrera likely was caught in the middle of the gang gunfire, police said, when the shots were fired apparently a half a block away.

"I think all this gang violence needs to stop. A bullet does not have no name. It can shoot anybody. It can shoot you, me, anybody," Rega told the ABC affiliate.

Investigators will also turn to surveillance images from a police camera for clues into the identity of the suspects.

"Our information at this time is the shooters were directly in this area, so we are going to send the tape in now to see if we can get an identification of the shooters," Capt. Ed Griffin, a spokesman for the Chicago Police Department, said.

Barrera's children are staying with relatives.

No one was in custody for the shooting, which occurred shortly before 6 p.m. Wednesday in the 4800 block of South Seeley Avenue, an area known for gang activity, police said this morning.

The victim, Leticia Barrera, 38, had just returned to her home with her three children, ages 2, 5 and 7, and was standing out front when shots rang out from about a half a block away, police said. She was hit in the head by gunfire but was not the intended target, according to police. The children were not hurt.

Barrera was taken to Stroger Hospital, where she was pronounced dead at 6:05 p.m. Wednesday, according to the Cook County medical examiner's office. An autopsy was scheduled for later today.

The woman was believed to have been about seven months pregnant, Chicago Fire Department Cmdr. Will Knight said.

Deering District Capt. Edward Griffin said police were looking for two males, believed to be in their teens, wearing dark hooded sweat shirts. A police source said the gunman was wearing a Wolfman mask.

A resident on the block said he heard nine shots and saw at least two males believed to be involved in the shooting, wearing Halloween masks and dark-colored clothing.

"I turned and saw the lady fall to the floor," said the resident, who declined to be identified.

Police said the suspects were standing under a police crime camera when the shooting occurred. Footage from the camera, installed because of the high crime rate in the area, will be reviewed by investigators, police said.

Lupe Alvarez, who lives a block away from the shooting, said: "It's just terrible. Why did they have to do it when there are kids around? We have a lot of questions."