A 14-hour standoff with police in Detroit has left three women and the gunman dead, Detroit News reports. In addition, three police officers are said to have sustained non-life-threatening injuries in the incident which began on Sunday night at around 10 pm, when two women were fatally shot during an argument.

On Monday, police used a robot to enter the home of the gunman, Lance Smith, 49, to confirm he was dead. Smith is reported to have died of a self-inflicted gunshot wound. He is said to have murdered a woman who is believed to be his girlfriend. She was found dead inside the home. Detroit Deputy Police Chief Elvin Barren says the other two slain women were related to Smith’s girlfriend. According to Barren, the women had shown up to help out during a domestic dispute and ended up victims themselves. They were taken to the hospital where they were pronounced dead.

Responding officers were caught in active gunfire. Initially, they did not return fire, as it was unclear from where the shots were coming. At first, police thought another suspect was shooting from a neighboring home, before they determined there was only one shooter.

Smith is said to have suffered from mental illness and does not have a criminal history. He did, however, have seven guns registered under his name.