“If people see him, they should not approach Card or make contact with him in any way,” Maine Public Safety Commissioner Mike Sauschuck told reporters at a news conference. 

At least 18 people were killed and 60 were injured, according to law enforcement sources. Some of those injuries were reportedly from a stampede, the sources said.

Officials urged residents of Lewiston and neighboring Auburn to shelter in place.

Authorities did not disclose any information about Card. The University of Maine confirmed that he studied engineering there from 2001 to 2004.

Maine court records show that a man named Robert Card who was born on the same date as the person of interest was charged with speeding in 2001 and 2002. No other criminal records were listed in the state’s electronic court records system or in several other public records databases.

A bulletin put out by the Maine Information and Analysis Center, a database for law enforcement officials, said Card was a trained firearms instructor and was believed to be in the Army Reserve.

It added that law enforcement said Card “recently reported mental health issues to include hearing voices and threats to shoot up the National Guard Base in Saco, ME.”

The bulletin said Card was reported to have been committed to a mental health facility for two weeks this summer and then released. NBC News has not been able to independently verify the bulletin’s statements about Card’s history.

Liam Kent, 24, told NBC News that he grew up about a mile away from Card’s family and would occasionally see him around town.

Kent said the family is well known in the area and operates a construction business and described them as “Second Amendment enthusiasts” who embrace a “‘don’t tread on me’ mindset.”

Law enforcement officials said they were reviewing some social media postings associated with Card.