LAWRENCE, Mass. -- The children of a man and woman found dead after a murder-suicide either heard or saw the deadly incident, Lawrence police said Sunday.

Francisco Santiago, 44, shot and killed his girlfriend, Flora Acosta, 39, and then turned the gun on himself in their home, police said.

Both died of wounds to the head from a small-caliber handgun, WCVB-TV in Boston reported.

Before the shooting, police said, Santiago sent their 10-year-old son upstairs to his aunt's home, but an 8-year-old daughter and an autistic teenage son remained in the apartment.

Neighbors heard four or five gunshots.

"We heard the children shouting, screaming, 'They killed her, they killed her'," neighbor Carmen Pizaro said.

Police found the autistic boy sitting on the couch next to his dead mother. He was covered with blood, and police initially thought he was a victim of the shooting.

Santiago was arrested in 2005 for assaulting Acosta, the television station reported. However, police said she let a restraining order expire.