Six people were shot in separate incidents around New York City on Monday night, leaving one critically wounded and the others recovering at local hospitals, according to police.

The rash of shootings marked a grim start to a hot week as temperatures soar in the first major heat wave of the year. Crime experts say warmer weather can drive gun violence as people tend to have more free time, drink more alcohol, gather in large groups and spend time outdoors — sometimes leading to tense conflicts that boil over.

The first shooting happened around 6 p.m. on 221st Street and Bronxwood Avenue in the Williamsbridge neighborhood of the Bronx, NYPD officials said. A 27-year-old man was shot in the hand, a 21-year-old man was shot in the back and left armpit, and a 33-year-old man was shot twice in his right leg, according to police.

All three were taken to Jacobi Hospital in stable condition, the officials said. Police did not immediately have a description of a suspect, and no arrests were made.

Around 8:30 p.m., police in St. Albans, Queens, responded to 203rd Street and 119th Avenue, where the NYPD said a 60-year-old woman was shot in both her shoulders. Police said she was taken to a local hospital in stable condition, and no arrests were made.

Not long after, around 8:45 p.m., police said a 29-year-old man was shot in his chest and left arm at the intersection of Lincoln and Liberty avenues in Cypress Hills, Brooklyn. First responders took him to Jamaica Hospital in stable condition, and NYPD officials described the suspect as a man wearing green shorts and a black hooded sweatshirt.

The last reported shooting victim of the night was a man who was shot in the head around 9 p.m. near East 162nd Street and Third Avenue in the Bronx’s Morrisania neighborhood. Officials said emergency medical workers transported him to Lincoln Hospital in critical condition.

Police did not immediately have information about the man’s age, and had no description of a possible suspect.

Shootings in New York City typically spike by as much as 30% in the summer, according to some criminologists. Christopher Herrmann, an associate professor at CUNY’s John Jay College of Criminal Justice who studies gun violence, previously told Gothamist that most shootings take place between 10 p.m. and 2 a.m on weekends.

The six people shot on Monday night were all shot before that window, including several before sunset, according to police.

“Monday nights are not traditionally a busy night of the week for gun violence, but with kids’ schools winding down and the temperatures picking up, more and more people will be spending more time outdoors, especially in the evening,” Herrmann said.

On Sunday night, two men were shot and killed in Inwood, Manhattan, the NYPD said. A third man was injured in the shooting, which police continue to investigate.

This is a developing story and may be updated.