Federal immigration officers shot and killed a man in Minneapolis on Saturday, setting off protests in frigid temperatures and prompting the Minnesota National Guard to be activated to assist local police, the Associated Press reported.

Minneapolis Police Chief Brian O’Hara said the department had limited information about what led up to the shooting. The AP reported that the man’s family identified him as Alex Pretti, a 37-year-old intensive care unit nurse who had previously protested President Donald Trump’s immigration crackdown in the city.

After the shooting, hundreds of protesters gathered and tensions escalated in the streets. The AP said protesters clashed with federal immigration officers, who wielded batons and deployed flash bangs during the confrontation.

The Minnesota National Guard was assisting local police at the direction of Gov. Tim Walz, according to officials cited by AP. Guard troops were sent both to the shooting site and to a federal building where federal officials have faced protesters daily, the AP reported.

The Department of Homeland Security said federal officers were conducting an operation. DHS spokesperson Tricia McLaughlin said in a statement that officers fired “defensive shots” after a man with a handgun approached them and “violently resisted” when they tried to disarm him.

In bystander videos that emerged soon after, the AP reported that Pretti was seen with a phone in his hand, and none of the videos appeared to show him with a visible weapon. O’Hara told reporters that police believe Pretti was a “lawful gun owner with a permit to carry.”

DHS Secretary Kristi Noem told reporters that Pretti had shown up to “impede a law enforcement operation,” while questioning why he was armed. The AP said she did not provide details on whether Pretti drew the weapon or brandished it at officers. Federal officials also said the officer who shot Pretti was an eight-year Border Patrol veteran.

The AP reported that Trump weighed in on social media after the incident, attacking Walz and the Minneapolis mayor. Trump posted images of a gun immigration officials said was recovered and asked, “What is that all about?” and “Where are the local Police? Why weren’t they allowed to protect ICE Officers?” He also said the governor and mayor are “are inciting Insurrection,” adding that their rhetoric was “pompous, dangerous, and arrogant.”

Pretti was shot just over a mile from where an Immigration and Customs Enforcement officer shot and killed 37-year-old Renee Good on Jan. 7, an event that had already sparked widespread protests in Minneapolis.

Pretti’s family released a statement saying it was “heartbroken but also very angry.” The family said the administration’s account of their son was “reprehensible and disgusting,” and it argued that Pretti was not holding a gun when attacked, saying he had his phone in his right hand and his left hand raised above his head while trying to protect a woman. The family also asked people to “get the truth out about our son” and said he was “clearly not holding a gun.”

In the aftermath, the police chief appealed for calm, telling residents, “We urge everyone to remain peaceful,” and calling for federal agencies operating in the city to show “discipline, humanity and integrity.” Gregory Bovino of U.S. Border Patrol said the officer who shot the man had extensive training, including as a range safety officer and in using less-lethal force.

Gov. Walz said he had no confidence in federal officials and that the state would lead the investigation into the fatal shooting. Drew Evans, superintendent of the Minnesota Bureau of Criminal Apprehension, said in a news conference that federal officers blocked his agency from the shooting scene even after it obtained a signed judicial warrant.

Protesters continued to gather at the scene. The AP reported that even as the worst of an extreme cold wave had passed, the temperature was still -6 degrees (-21 Celsius) at midday. After the shooting, protesters chanted “ICE out now” and “Observing ICE is not a crime,” and later hundreds of people gathered quietly by a growing memorial at the site, with some holding signs reading “Justice for Alex Pretti” and others chanting both Pretti’s and Good’s names.

The AP also reported a correction: the age of the man who was shot was corrected to 37, based on information from the police chief. The AP previously reported his age as 51 based on a hospital record.