olice were conducting a sprawling manhunt on Monday for a gunman suspected of carrying out a series of "cold-blooded" shootings of homeless men on the streets of Washington and New York.

The string of attacks, 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.

"The work to get this individual off our streets before he hurts or murders another individual is urgent," Washington Mayor Muriel Bowser and New York Mayor Eric Adams said in a joint statement.

"It is heartbreaking and tragic to know that in addition to all the dangers that unsheltered residents face, we now have a cold-blooded killer on the loose, but we are certain that we will get the suspect off the street and into police custody," they said.

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

Police said the first shooting took place around 4:00 am on March 3 in northeast Washington. The victim was taken to hospital with non-life threatening injuries.

A second homeless man was shot and wounded five days later, also in northeast Washington, police said. He also suffered non-life threatening injuries.

The next day, 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 at around 4:30 am, police said.

"He's alive today because he woke up after he heard the first gunshot and started yelling," Adams told reporters.

Then, shortly before 5:00 pm, police in the same neighborhood found the lifeless body of another man in a yellow 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 around 6:00 am and then opening fire with a pistol.

'Heinous crime'

"Our homeless population is one of our most vulnerable and an individual preying on them as they sleep is an exceptionally heinous crime," New York police commissioner Keechant Sewell said.

"We will use every tool, every technique and every partner to bring the killer to justice."

Washington police offered a reward of $25,000 for information that leads to an arrest.

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) offered an additional $20,000 reward while New York put up $10,000.

Adams, the New York mayor, urged the city's thousands of homeless people to contact municipal agencies that can help them find sleeping accommodation.

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.

"People only stay in the subway," said the Coalition for the Homeless, "because they have no better place to go."

"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.

"Instead of subway sweeps, the City and State must immediately open the promised housing and Safe Haven beds so that unsheltered New Yorkers have a safer place to stay inside," Simone said.

In Washington, a 53-year-old homeless man who identified himself only as Troi told AFP that he was "not more afraid than before."

"Lots of negative things happen when you are homeless," said Troi.

"(But) it hurts when it's close to you," he added. "We should protect each other at night, to be aware of any stranger that comes around, but there is no solidarity."

In October 2019, a homeless man wielding a metal pipe beat four other homeless people to death in New York and left a fifth man in critical condition.