Four people were shot, three of them fatally, by a man who appeared to fire randomly over about two-and-a-half hours in Detroit, police in the US said.

Officers arrested a suspect on Sunday night after an hours-long manhunt involving multiple federal agencies.

Police Chief James White said tips led officers to the suspect, but he did not immediately release more information about the suspect or the arrest.

Mr White earlier said investigators had traced all four shootings to one firearm but believed them to be random because there was no apparent connection between the victims.

One person had been waiting for a bus and another had been walking their dog.

He said police discovered a woman in her 40s who had been shot multiple times at around 4.45am on Sunday. While officers were investigating that fatal shooting, a witness reported that a 28-year-old man had been shot multiple times nearby, Mr White said.

A third victim, a woman in her 40s, was found in the area at around 6.50am. She died after also being shot multiple times, police said.

At around 7.10am, an elderly man reported that he had seen a man peering into vehicles. When the elderly man told the person to get away from the cars, the gunman fired at the elderly man, who was shot once and survived, police said.

Mr White and Mayor Mike Duggan had urged residents to be alert and call police with any information.

“The suspect already shot four people. Please call immediately … Someone out there knows who this is,” Mr Duggan said.

The mayor later credited “critical information from the community” and multiple law enforcement agencies with helping Detroit police take the suspect into custody.

“As we mourn our three neighbours who were killed, we should take the time to appreciate all the men and women in law enforcement whose work today made sure no other families will suffer at the hands of this shooter,” Mr Duggan tweeted.