A Brooklyn man accused of killing an 86-year-old and injuring three other men in a series of shootings while riding a scooter in New York City is charged with murder and attempted murder, police said Sunday.

In all, six apparently random shootings occurred in Brooklyn and Queens on Saturday, according to police.

The motive of the alleged gunman, identified Sunday as 25-year-old Thomas Abreu, was unknown, police said. Police arrested Abreu without incident Saturday. The New York Police Department pulled an image of the gunman from video and sent it to officers, who spotted him a couple hours after the first shooting, police said.

Police confiscated a scooter and a 9 mm handgun with an extended magazine. Abreu was charged with murder, two counts of attempted murder and six counts of criminal possession of a weapon.

The shootings began around 11:10 a.m., when the gunman shot a 21-year-old man in the shoulder in Brooklyn. The man was brought to a hospital and was expected to survive, police said.