INDEPENDENCE, Mo. (AP) — Three men broke into a house in a Kansas City suburb early Friday and fatally shot a woman, her son and her boyfriend, police said. A fourth victim was critically injured.

No motive has been established for the shooting at the small home in Independence but it was not a random act, Independence police Capt. John Cato said.

"This was an armed attempted residential robbery," Cato said. "They probably knew or at least were associated with one another."

Cato identified the dead as 48-year-old Maria Hernandez; her boyfriend, Thomas Madrigal; and Hernandez's 20-year-old son, Antonio. The fourth person was not identified.

Police are searching for the suspects, and at least two of them could be armed, Cato said.

Charlene Myers, 29, who lives a few houses away, said she didn't hear any gunshots and described the neighborhood as very safe and quiet. Myers mother lives across the street.

"When my mom called me and told me people got shot there, I was like 'What?'" Myers said.

She said the family that was attacked had arrived in the street in the past year.