A US man being fired from his job shot dead five co-workers at a factory on the outskirts of Chicago and wounded five police officers before being gunned down, in the country's latest mass shooting.

The gunfire took place at 1:24 pm (1924 GMT) at the Henry Pratt Company in Aurora, Illinois, a suburb 40 miles (65 kilometers) west of Chicago, the country's third-largest city.

Police named the suspect as Gary Martin, 45, of Aurora. He was a 15-year employee of the company and "information that we have indicates that he was being terminated today," said Aurora Police Chief Kristen Ziman.

The shooting came the day after Nancy Pelosi, the powerful speaker of the House of Representatives, said gun violence is a "national emergency" far more real than the one President Donald Trump ultimately declared Friday to build his wall at the Mexican border.

Police Chief Ziman did not have further details about why Martin was being fired, whether the killing was pre-meditated, or whether the victims were involved in his dismissal.

In a tweet, President Trump praised the "great job by law enforcement in Aurora, Illinois" and sent "heartfelt condolences to all of the victims and their families. America is with you!"

A coalition of gun control advocacy groups condemned the murderous attack, saying it was the 198th mass shooting in the last 10 years.