Colorado school shooting: Student who wounded two students before killing himself may have had grudge against teacher

One student remains in a serious condition, while another suffered minor injuries

A high school in suburban Denver became the scene of another deadly shooting on Friday night when a teenager opened fire, wounding two students before killing himself.

The gunman was indentified by police last night as Karl Halverson Pierson.

The emergency lockdown at Arapahoe High School in Centennial on the south side of the city came on the eve of the first anniversary of last December’s primary school shooting at Sandy Hook School in Connecticut which left 26 people dead including 20 children.

Police officials said the alert started when a student, whose name had not been released, entered the school intent on confronting a teacher. The teacher was informed and immediately left the grounds.

"He knew he was the target and he left that school in an effort to try to encourage the shooter to also leave the school," the sheriff said. "That was a very wise tactical decision."

The shooter then shot two students, including a girl who was in serious condition. The other student suffered minor injuries and was expected to be released from the hospital on Friday night, he said.

A suspected Molotov cocktail was also found inside the school, Arapahoe County Sheriff Grayson Robinson said. The bomb squad was investigating the device.

Deputies and police officers who responded to the school immediately entered to engage the gunman as students were kept locked in their classrooms.

Several other school districts in the Denver area went into lockdown.

The practice of sending law enforcement directly into an active shooting was developed in response to another Colorado school shooting that shook the nation: In 1999, two teenage shooters killed 12 classmates and a teacher at Columbine High School before killing themselves.

Arapahoe High School is just eight miles from Columbine.

Additional reporting by PA