More than 50 New Hampshire state troopers are helping Maine authorities look for a man suspected of killing more than a dozen people in a mass shooting in Lewiston, Maine, on Wednesday night.

As of Thursday afternoon, New Hampshire officials said there is no known threat to the state but police remain vigilant and ready to respond.

“We are taking proactive caution and are positioned strategically in the event that we receive some information that we may have more of a heavy involvement on our side of the line,” said Police Captain Victor Muzzey of the Justice Information Bureau. “We do not have roadblocks set up but we are looking for anything suspicious or out of place that might cause us to question.”

The suspect, Robert Card, 40, of Bowdoin, Maine, remains at large and is considered armed and dangerous.

“New Hampshire state officials have been in touch with our counterparts in Maine to offer and provide any medical and safety resources needed as they manage this horrific situation,” said Gov. Chris Sununu in a statement.

State hospitals are prepared to receive victims if needed but have not received specific requests to do so, said Vanessa Palange, community outreach coordinator for the Homeland Security and Emergency Management division of the state Department of Safety.

State police will continue to monitor the situation and assist Maine law enforcement until the suspect is apprehended or found. Just before 8 p.m. Wednesday night, the Maine Department of Safety requested the use of the state’s helicopter and aviation unit. Around 8 a.m. on Thursday morning, more than 50 New Hampshire State Police from the major crime unit, the aviation unit and the SWAT team were dispatched to the area of Lewiston.

“The Maine authorities have been out and active all night and we wanted to send them some relief to get some rest and recuperate a little bit,” Muzzey said. “We suspect that cycle will go on for as long as this takes. It’s an all hands on deck situation and we will continue to rotate people through as we need to to make sure we can keep the continuity of service and safety.”

Sununu ordered flags to fly at half-staff at all public buildings.

“The State of New Hampshire stands with the people of Maine – they are our friends, families, and neighbors,” Sununu said Thursday morning. “State officials have been in constant contact with our counterparts in Maine, and have been assisting in the response and manhunt since last evening. We will continue to provide as many resources as necessary so that justice is served.”

Armed with a semiautomatic rifle, Card pushed open the doors of a family-style bowling alley around 7 p.m. Wednesday night and began firing. Less than an hour later, he entered a restaurant down the road and continued his rampage before disappearing into the night.

According to the Associated Press, at least 18 people were killed and 13 were wounded in the shootings. At the time of the shooting, the bowling alley was filled with kids and their families as part of a children’s bowling league.

A police bulletin identifying Card as a person of interest in the attack described him as a firearms instructor believed to be in the Army Reserve and assigned to a training facility in Saco, Maine.

The document, which was circulated to law enforcement officials, said that Card was committed to a mental health facility for two weeks over the summer. It did not provide details about his treatment or condition but said that Card reported “hearing voices and threats to shoot up” the military base.

Material from the Associated Press was used in this report.