What started as a crash involving a federal agent led to tense confrontations between residents and federal agents carrying out immigration enforcement activities in northwest suburban Elgin this weekend.

An hour-long standoff led to federal agents deploying chemical irritants on people confronting them in an Elgin neighborhood on Saturday morning.

Erika lives in the apartment complex in Elgin at the center of the confrontation. She said the commotion started in the front yard around 9 a.m. Saturday, with federal agents and a crowd gathering.

"It scared me," she said.

According to Elgin police, federal immigration enforcement agents were involved in a car crash, and a person in a different car involved in the crash ran away to the apartment complex in the 1600 block of Maple Lane.

Mari Elena and Eddy are part of a rapid response group in Elgin and were among dozens who arrived at the scene on Saturday, monitoring the agents' activity.

The confrontation led to agents tackling a person to detain them and using chemical irritants to try to disperse the crowd.

"They tear-gassed at us, and then more people, more people started showing up protesting, and then more agents," Mari Elena said.

Seven people had to be treated medically on scene, according to Elgin police.

"We didn't think that today was going to happen the way it happened today," Eddy said.

The incident comes during an uptick of activity this weekend, including these incidents of agents detaining people on Friday in Cicero, Illinois.

Elena said that while recent weeks have seen immigration enforcement operations slow down with the departure of leaders like Border Patrol's Greg Bovino, the incidents this weekend highlight that agents remain active.

"I just feel like, communities, we still need to be, like, on alert and still be united," she said.

Elgin's Mayor Dave Kaptain said the actions by those agents angered him.

"It discourages me, it disgusts me, the actions of the federal agents that came to our city," Kaptain said. "This city was founded on its diversity and self-respect and mutual respect between our residents. These ICE people have not shown that respect to this community, and it really angers me."

According to Elgin police, about 30 calls were received related to the incidents.  

"The Elgin Police Department will continue to respond to any calls for service and determine the appropriate action within the parameters of the Illinois Trust Act, which prohibits Elgin officers from assisting with federal immigration enforcement operations," the department said. 

CBS News Chicago reached out to the Department of Homeland Security for more on the incidents that took place in Elgin on Saturday. The department has not commented.

It remained unknown Monday morning how many people were detained.