A woman is waiting for the bus on Sunday morning, a man is walking his dog – then both are hit by a bullet. A gunman fired on four people in the US metropolis of Detroit, killing three. What drove the perpetrator is so far completely unclear.

In the metropolis of Detroit in the US state of Michigan, a shooter apparently killed three people with shots fired at random. After a large-scale search by the police and numerous tips from the population, the alleged perpetrator was arrested late on Sunday evening just a few hours after the crime.

Detroit Police Chief James White said the suspect fired multiple shots at two women and a man in different parts of the city early Sunday morning. A man then observed the shooter peering into cars. When the man tried to stop him, the attacker fired a shot at him. Three of the four attacked died, the police said to local media.

The shooter apparently chose his victims “very arbitrarily,” Police Chief White said at a press conference. “One was waiting for a bus, one was walking their dog and one was just on the street.” According to Detroit Mayor Mike Duggan, officials from various agencies had initially unsuccessfully searched for the shooter. Only the search call was finally successful.

The Detroit shooting wasn’t the only case of deadly gun violence in the United States on Sunday. In the Texan city of Houston, a man shot dead three people, according to authorities. The suspect set fire to several apartments, then lay in wait and shot people fleeing the burning apartments, Houston Police Chief Troy Finner said at a press conference.

The incoming firefighters also had to take cover from the shooter. The police finally shot the attacker, Finner said.