Three law enforcement officers in Chicago were shot on the city’s South Side on the heels of a violent holiday weekend that racked up shootings in the triple digits.

The officers, two ATF Chicago agents and one Chicago Police Department officer, were driving in the Morgan Park neighborhood, near an on-ramp to Interstate 57, just before 6 a.m. when they were fired upon by another vehicle, Chicago Police Superintendent David O’Neal Brown told reporters Wednesday morning. The officers were undercover and in an unmarked car, Brown said.

The officers’ injuries are not life-threatening. One of the ATF agents was struck in the hand, the other was hit on the side of the torso and the police officer was grazed in the back of the head, Brown said. They were taken to Christ Medical Center and last reported in stable condition, said Tom Ahern, deputy director of the police department’s news affairs and communications,

One of the ATF agents is female, while the other two officers are male, and all three are senior officers, he added.

The suspect’s vehicle has been located, but investigators are still searching for the suspect, Brown said.

Brown declined to provide details on the case the officers were working to avoid compromising the investigation.

The attack marks brings the tally of officers shot in Chicago this year to 36, Brown said. The shooting comes after a deadly Fourth of July weekend in the city, when 100 people were shot, 18 of whom died, including a 15-year-old boy, ABC Chicago station WLS reported. Two Chicago Police officers and five children 13 and younger were among the injured.

Brown said Tuesday that Chicago officers were “performing at the highest level” and are “risking everything to protect the people of Chicago.”

“They are doing their part, and no one would do what these officers are doing right now,” Brown said. “This is a very challenging time to be in law enforcement right now. They are rising to the challenge, doing all they can. The work they do is extremely dangerous.”

Speaking from outside the hospital, Chicago Alderman Matt O’Shea urged President Joe Biden to come to Chicago and offer additional assistance to the city, saying that 100,000 armed gang members who “have absolutely no fear, no respect for life” are wreaking havoc on the city. Residents are scared to let their children play outside, he said.

“Our communities are under siege,” he said. “Our police officers are under siege. They’re outmanned and they’re outgunned.”

Biden is expected to be in the Chicago area on Wednesday. He’s scheduled to meet with Mayor Lori Lightfoot upon landing and will visit Crystal Lake, a city about 45 miles northwest of Chicago, in the afternoon.

ABC News’ Cheryl Gendron, Rachel Katz and Alex Perez contributed to this report.