At least four police officers and multiple civilians have been shot at a steel mill in Aurora, Illinois.
Police arrested a gunman after the shooting at the Henry Pratt Company.
Schools in the area were on lockdown during the attack, which took place around 3pm local time.
The culprit is believed to be an employee of the company, according to survivors. There would have been around 30 people in the building at the time of the shooting.
John Probst, an employee who escaped the building, told ABC7 Chicago that he saw a coworker holding a pistol with a green laser beam.
He told the local news station that he saw other coworkers injured and that the shooter was firing indiscriminately.
Mr Probst added: "One of the guys was up in the office, he said this person was shootin', and, he come running down and he was bleeding pretty bad, and the next thing you know he was walking back and forth, I heard more shots, and we just left the building."
Witnesses reported seeing at least 30 police cars at the plant in southwest surburban Aurora.
Rush Copley Hospital tweeted that they had received two victims with non-life-threatening injuries.
The officers who were injured are in a stable condition, according to City of Aurora Director of Communications Clayton Muhammad.
The local school district told parents: "There are reports of an active shooter at the Henry Pratt building near Cleveland and Prairie just east of Luigi's Pizza, as a result, we are holding all district students in place for their safety, there is a police presence in the area.
"Per directions from the county sheriff, the District has been advised to go into soft lockdown situation across the district.
"Teaching will continue with reduced movement. Normal operations will resume when the soft lockdown has been lifted. No one will be allowed to leave or enter our buildings until the lockdown has been lifted."
