The Central Michigan University student police say shot and killed his parents Friday morning used his father's gun, police said Saturday.

James Eric Davis Jr., a 19-year-old sophomore, was arrested early Saturday morning for the deaths of his parents.

CMU Police Chief Bill Yeagley said during a Saturday press conference the gun was registered to Davis' father, James Eric Davis Sr., a Bellwood, Illinois, police officer. The chief said the weapon, which was found at the scene of the shooting, was on campus in violation of the university's weapons policy, which states only law enforcement on active duty are able to be on campus armed.

"What we know for sure that the gun was registered to his father, and we saw that for sure he came from the parking lot into the residence hall," Yeagley said.

Police say James Eric Davis, Sr., and Diva Jeneen Davis had picked up their son Friday morning from a local hospital. Friday was the last day before CMU's spring break. Many students had already left campus while others were planning to leave Friday.

Yeagley said police's interaction with Davis began Thursday, when he came to a CMU community policing officer stationed in his residence hall and told the officer he was frightened that someone he knew got a gun and he was worried someone was going to hurt him.

"Mr. Davis was very vague..." Yeagley said, "Everything was very vague, so we got other officers involved."

Michigan State Police cars are on the scene of the shooting at Central Michigan University on March 2, 2018 in Mount Pleasant, Michigan. Rachel Woolf/Getty Images

Yeagley said officers obtained a name and reviewed footage of Davis riding down the elevators and laughing with this individual, but when they stopped the individual Davis named to see if there was threat, police determined this person had no registered weapon and they were not able to see risk for anyone.

When officers told Davis they determined there was no threat, but asked how they could make him feel safe, Yeagley said Davis informed them he would be going home in the morning.

However, around three to four hours later, Yeagley said officers in the area saw Davis in the hallway with a number of suitcases and bags, acting in a fashion "that is not reasonable or logical."

An officer then asked Davis to call his parents, and Yeagley said the officer spoke to his mother about what they observed and shared concern that it might be drugs. Yeagley said Davis' mother shared this concern and said she and his father would be coming up to campus right away, officers then took Davis to the hospital to get checked out.

"He stayed until the following morning when he was picked up by his parents and came back to Campbell Hall..." Yeagley said. "There is one witness who stated Mr. Davis was seen coming from the parking lot into the residence hall with a gun in his hand."

Yeagley said the gun was then taken up to the fourth floor of Campbell Hall where police believe he shot and killed his father and his mother, before leaving on foot and moving north along the railroad tracks.

Police said cameras located in the common area and exits of the dorm captured Davis Jr. leaving the dorm, heading north and running along train tracks. Police said they had recovered pieces of clothing along the tracks.

Yeagley said police received a tip from a train company that operators noticed a subject standing near the tracks just after midnight, and reported the suspicious activity.

Police then responded and took Davis into custody. Yeagley said he was appeared to be hypothermic and was not making sense, so police transported him to the hospital.

Michigan police officials survey nearby neighborhoods as police continue to search for a suspect near Central Michigan University on March 2, 2018 in Mount Pleasant, Michigan. Rachel Woolf/Getty Images

After the shooting, authorities identified Davis as the suspect. More than 100 officers from various agencies searched into the night for him. The school's campus and most of the city of Mt. Pleasant, Michigan, where the university is located, were on lockdown while police from local, state and federal agencies searched the area.

CMU President George E. Ross said the university will be responding to this incident by re-doubling their safety efforts and providing students with professional counseling available after they return from spring break.

Ross commended the law enforcement officers from various agencies, lauded the campus community for locking down within minutes and sheltering in place, and also extended his condolences to the Davis family.

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He said CMU's campus and community are traumatized after yesterday.

"We read about shooters on campuses across this country and communities, we talk about it, we practice what would happen if it happens, here, and never envisions it could happen at CMU. We are a safe community, we are a safe campus. but yesterday we demonstrated our ability to deal with the inconceivable," he said.

"...We're not done yet, there were thousands of people on campus yesterday, and they're going to be dealing with this for the rest of their lives."

Ross also thanked Gov. Rick Snyder for his response to the incident yesterday and for coming to the campus.

Friday was the last day before CMU's spring break. Many students had already left campus while others were planning to leave Friday.

CMU is a university of about 25,000 students, located in mid-Michigan. It is about an hour north of Lansing, the state capital and about 2½ hours northwest of Detroit.

Contributing: Christal Hayes, USA TODAY; The Associated Press