JAFFREY – Monadnock State Park was closed Tuesday morning after authorities discovered a lost hiker likely had a gun in his possession.

The 21-year-old man was found hours later in the white cross trail, dead of what is believed to be a self-inflicted gunshot wound, said Fish and Game Lt. Craig Morrocco.

“We received a call about 7:15 a.m. from Monadnock State Park,” Morrocco said.

The vehicle of a man who arrived late in the day, around 4:30 p.m., on Monday was still in the parking lot. Park rangers said they had unsuccessfully attempted to dissuade the man from hiking that afternoon, it was nearing nightfall and he seemed unprepared to hike, Morrocco said.

After running his license plate number, Fish and Game learned Keene police were looking for a Keene State College student from Alexandria who lived off-campus in Keene with a roommate.

“We found out that he had a ‘be on the lookout’ notice for him by the Keene Police Department because his parents were concerned and his roommate was concerned about him,” Morrocco said. “He had not returned home and had been acting strangely lately.”

About 10 Fish and Game officers and state park employees, along with one volunteer and a Jaffrey police officer searched the park for the student.

After searching his car, authorities believed he was in the possession of a gun, Morrocco said, so the park was closed to hikers around 9:25 a.m.

“We were led to believe the victim had a firearm, so I made the decision to close the mountain to hikers for their safety,” Morrocco said. “Hikers were directed to other state parks in area.”

Around 1 p.m., the student was found dead on the white cross trail. Jaffrey police are still investigating and the medical examiner, who conducted an autopsy Tuesday afternoon, has yet to determine the cause of death, but it appears he died of a self-inflicted gunshot wound, Morrocco said.

Monadnock State Park plans to reopen tomorrow, but that trail is to be closed to hikers, he said.