US police were conducting an “urgent” manhunt on March 14 for a gunman suspected of shooting homeless men on the streets of Washington and New York in a series of “cold-blooded” attacks.

The string of shootings, which took place in the middle of the night over a period of 10 days this month, have left two men dead and three wounded.

Washington Mayor Muriel Bowser and New York Mayor Eric Adams, at an unusual joint press conference in the nation’s capital also attended by the police chiefs of the two cities, urged members of the public to come forward with information they may have about the suspect.

“Our unsheltered residents already face a lot of daily dangers and it is unconscionable that anybody would target this vulnerable population,” Bowser said. “We’re calling on anyone who has any information to reach out to our tip lines.”

Bowser said a $70,000 reward had been offered for information leading to an arrest – $25,000 by the Washington police, $25,000 by the New York police and $20,000 by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF).

Adams, the New York mayor, said the gunman “is carrying out a premeditated act, shooting innocent people” and the series of attacks were “cold-blooded.”

Police released multiple pictures and surveillance video of the suspect – a shaven-headed and bearded man dressed all in black.

Police said the first two shootings took place in northeast Washington, on March 3 and March 8. Both victims suffered non-life threatening injuries.

On March 9, a homeless man was found dead in northeast Washington with stab and gunshot wounds, police said. His tent had been set on fire.

On Saturday, a 38-year-old man was shot in the arm in Lower Manhattan.

“He’s alive today because he woke up after he heard the first gunshot and started yelling,” Adams said.

Police in the same neighbourhood later found the lifeless body of another man in a sleeping bag. He had been shot in the head and neck.

Video surveillance footage captured that attack, showing the shooter, who was wearing blue surgical gloves and a black balaclava, kicking the sleeping man and then opening fire with a pistol.

‘Depraved person’

“What we know is we have a depraved person that is targeting our unhoused residents,” Washington police chief Robert Contee said.

New York police chief Keechant Sewell said her department was devoting “every available resource to this case”.

The Washington and New York mayors urged the tens of thousands of homeless people in their cities to seek shelter.

“Our shelters are safe,” Bowser said. “They have space.”

“Anyone who wants shelter will get shelter in the city of New York,” promised Adams.

New York’s homeless population has grown in recent years, and Adams announced a plan just weeks after taking office in January to move them out of the city’s vast subway system, where many sleep on frigid nights.

His proposal drew sharp criticism from some non-governmental organizations.

“Many unsheltered New Yorkers choose to bed down in the subways because that is where they feel the most safe in the absence of housing,” said Jacquelyn Simone, policy director for the Coalition for the Homeless.