A shotgun-wielding student police say was bent on harming a particular teacher instead shot two fellow students at Arapahoe High School in suburban Denver on Friday afternoon.

Police said the targeted teacher probably saved lives by fleeing the school in an attempt to lure the gunman out of the building.

The gunman, who later killed himself, entered the school from the student parking lot. Police said he came through the door with the shotgun in hand about 12:30 p.m. MT and began asking for the teacher by name.

"He made no effort to try and hide or conceal (the gun)," said Arapahoe County Sherriff Grayson Robinson. "Word got around immediately that he was looking for a specific teacher."

The gunman fired an unknown number shots, injuring two students, as he hunted for the teacher, police said. A female student was in serious condition and undergoing surgery late Friday. A second student suffered minor wounds and is expected to be released from the hospital this evening, Robinson said. It was initially reported that the female student tried to confront the gunman, but police later said that part was still under investigation.

Officers responding to the call rushed students out of the building while trying to locate the gunman. They found him dead about 20 minutes later from an apparent self-inflicted gunshot wound, Robinson said.

Sixteen-year-old Abbey Skoda said she was in chemistry class when she heard a loud bang out in the hallway.

“It was a gunshot. Then another one came right after it,” Skoda told Yahoo News. “My teacher turned off the lights, locked the doors and we prayed.”

They huddled together under science lab tables.

“I was praying the whole time, ‘God not today, not today. There is so much I want to do yet,’” Skoda said.

Police declined to immediately identify the suspect or victims other than to say they were all students at the school. But Skoda told Yahoo News that students immediately recognized the gunman.

“He had strong opinions about gun laws and he was bullied a lot,” said Skoda. She said she once had a class with the gunman.

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Robinson said officers believe the suspect acted alone. He said police also found a possible Molotov cocktail at the scene which they were examining. Meanwhile, detectives were searching the gunman’s home for a possible motive.

“We have no indication that it is tied to Sandy Hook,” said Robinson, referring to Saturday’s one-year anniversary of the school shooting tragedy in Newtown, Conn.

Arapahoe High School, home to more than 2,100 students, is located in Centennial about 15 miles south of Denver. Aerial images from news helicopters showed scores of students filing outside of the school and getting pat-downs from police officers.

"I just think it is really messed up that someone would do these things," said student Ryan Schaefer, who was off campus when the shooting occurred.

The high school is 15 miles from the Aurora movie theater where a dozen people were shot to death in July 2012. Columbine High School, where two teenage gunmen killed 12 students and a teacher in 1999, is about eight miles away.

Colorado Gov. John Hickenlooper lamented what he called an “all too familiar sequence where you have gunshots and parents racing to the school and an unspeakable horror in a place of learning.”

(Yahoo reporter Tim Skillern contributed from Centennial, Colo.)