Ziman said during a brief news conference that officers were “fired upon immediately” while responding to the 29,000-square-foot warehouse at about 1:30 p.m. Central time. Police said that they believe Martin was an employee at the warehouse.
The company had fired Martin on Friday before the shooting, police said.
Police say the five wounded officers were taken to local hospitals, two of whom were transferred to trauma centers. Police did not specify if any others were injured or how many. Some of the victims had been identified as of Friday night, but police had not released the names out of respect for the families.
Police said Kane County opened an investigation into the shooting with support from the Bureau of Alcohol, Tobacco, Firearms and Explosives, FBI and the state’s attorney’s office.
Ziman said the gunman used a Smith and Wesson handgun, though it was not clear if the gun was registered in his name.
Gabriel Gonzales, an Iraq War Marine veteran who can see the Henry Pratt warehouse from his front yard, said the number of police vehicles, flashing lights and armored cars Friday afternoon were giving him flashbacks.
"When you are a combat zone you expect it,” said Gonzales. “I've never seen this many police officers anywhere."
He was watching his grandchildren, who were mesmerized by the activity unfolding through the window, and worrying about their brother Anthony, whose school was put under lock down.
“My grandson had a school lockdown at 8 years old. I mean, can you believe that?” Gonzalez said. “Back when I was a kid, it was just tornadoes.”
At the news conference, Aurora Mayor Richard Irvin said the shooting marked "a sad day in the city."
“For so many years, we’ve seen similar situations throughout our nation,” he said. “To experience it firsthand is even more painful.”
Illinois Gov. J.B. Pritzker (D) lauded the efforts of law enforcement officers and first responders before lamenting the “epidemic of gun violence that continues to ravage so many communities.”
The victims’ families, he said, “join a group that should not exist, yet continues to grow.”
Tiffany Probst, 38, a legal assistant said her best friend saw a post on Facebook about the shooting and she started texting “that your dad might be inside!”
Her father, John, has worked as a machinist in the building for over 40 years. He has three grown children and has five grandchildren. Probst raced down to the factory, but it was blocked by police.
“I knew there was no way to call him because he’s old school and never has a cellphone,” then she heard from friends that her father was giving TV interviews and talking with the police.
“He’s safe and talking to the news,” she said. “He’s not much of a talker, but when it comes to this, I can tell by his voice he’s real shaken up. We are looking forward to giving him a hug.”
Sen. Tammy Duckworth (D-Ill.) tweeted Friday that she was following the situation. “This is a scary, sad day for all Illinoisans and Americans,” Duckworth wrote. “Thank you to the brave first responders who risked their lives this afternoon and apprehended the shooter.”
“My heart breaks for Aurora,” Sen. Richard J. Durbin (D-Ill.) tweeted. “I’m tracking updates on the situation with my staff. Thank you to the members of law enforcement who are responding to the emergency.”
Nancy Caal, who works at Erwin’s Truck Repair near the scene of the shooting, told The Washington Post that she heard the din of sirens as police cars and ambulances rushed to the building behind hers.
She and two others put the shop on lockdown when they saw heavily armed officers heading toward the adjacent Henry Pratt warehouse.
"Nobody told us nothing,” she said. “But we closed the gates and locked down the shop.”
News reports of an active shooter there confirmed their fears shortly after.
“We are kind of nervous,” Caal said. “It looks like something big is going on out there.”
Additional details were not immediately available.
Mark Berman and Julie Tate contributed to this report.
Correction: A previous version of this article misspelled the name of Aurora Police Chief Kristen Ziman.