Kansas City: A man killed five people, including three of his children, before fatally shooting himself, and a fourth child has life-threatening wounds, police said.

The man killed one woman, apparently his cousin, then went to another home and shot his longtime girlfriend, their four children and himself on Saturday, Captain Rich Lockhart said. Police did not immediately identify the shooter or the women. Relatives identified the shooter's girlfriend as Shanika King, who was in her 30s.

The slain children were a girl, 14, and two boys, ages 1 and 11, police said. An 8-year-old boy was in critical condition with a gunshot wound to the face.

Witnesses identified the first victim, a woman in her mid-30s, as the shooter's cousin, Lockhart said. The woman's son told police a man came to the door and asked to see his mother. The boy said he heard a "pop," but thought it was fireworks.

After the man left, the boy found his mother had been shot, Lockhart said. About 15 minutes later, police received a call from a woman who said her daughter's boyfriend had called her to say he had shot her daughter and grandchildren.

Two of the couple's other children had spent the night at their grandmother's house, said King's aunt, Janna Walker, who lives nearby in the neighbourhood, about five miles east of downtown Kansas City.

Kim Drew, a neighbour whose 13-year-old son was a friend of the slain children, described the shooter as a controlling man who wanted things done his way.