SALT LAKE CITY (AP) — An Army National Guardsman left a suicide note in his northern Utah home before killing a college student and one other person early Monday, then fatally shooting himself at another home, authorities said.

Jared Tolman, 23, wrote that he was sorry, and that what he was about to do was selfish, said Logan Police Lt. Rod Peterson.

He is reported to have sent a series of unanswered text messages to Mackenzie Madden before he kicked down the door of her apartment two blocks from Utah State University shortly after midnight.

He then fired an assault rifle multiple times at Madden and a 25-year-old man, both people he knew, police said.

Madden, 19, was a sociology major at the university in Logan, a city of about 48,000 people 80 miles north of Salt Lake City. Officers responding to 911 calls found her and Johnathon Jacob Sadler dead inside the unit.

It's unclear if Tolman knew beforehand that Sadler was in Madden's home, Peterson said.

The gunman then went to another apartment a few miles away, authorities said, to look for a man he believed was involved with Madden. But the man was not home because he was staying with family.

At that point, "Tolman turned the gun on himself," Peterson said.

Two other people were in that apartment at the time and called 911.

Investigators found the suicide note Monday. In it, Tolman imparted his belongings to his parents.

Phone messages left by The Associated Press with a household in Washington state believed to belong to Tolman's family were not immediately returned.

Police said the relationship between Tolman and Madden was unclear. No motive was released, and investigators gave no further details about the text messages he sent her.

Tolman graduated from Utah State University in May with a degree in political science, university spokesman Tim Vitale said.

He joined the National Guard in 2009, guard spokesman Steven Fairbourn said. He was assigned to a support battalion for the 19th Special Forces Unit, where his chief duty was handling laundry.

Tolman had no history of disciplinary issues, Fairbourn said.

Logan police said the same gun was used in all three shootings Monday. They did not confirm whether Tolman owned the assault rifle, but said it was not a government-issued weapon.

Madden was registered for classes this fall and was set to graduate in December, Vitale said.

She interned with Logan police in fall 2013, where she compiled research on active shooter situations, Lt. Brad Franke said.

"She wanted to save the world. I'm personally just shocked and saddened by this terrible loss," he said. "She was a great kid."

Sadler had no relation to the school.

The university functioned as normal Monday, Vitale said.