A man wielding a sharp-edged weapon killed a teacher and himself in front of students in a Wyoming community college classroom on Friday, causing a campus wide lockdown.
The assailant had killed another person elsewhere shortly before the attack at the school, authorities said.
Police found the suspect and the male teacher dead at a science building on the Casper College campus, which was locked down for about two hours, school and police officials said.
The other victim was found about two 2 miles (3.2 kilometers) away.
Casper police chief Chris Walsh said the murder-suicide took place in a classroom with students present, but he did not know how many students or what the class topic was.
He said investigators do not know the motive for the killings.
Walsh said an "edged weapon" was used it at least one of the killings, but he did not offer specifics, and it wasn't clear if the same or a similar weapon was used in all of the deaths.
The attacker wasn't believed to be a Casper College student and it appeared he knew the victims, Walsh said.
He didn't identify the suspect or victims but said the victims were a male and a female.
He added authorities don't believe there is any further threat to the community.
"I want to emphasize that this is a horrible tragedy," Walsh said. "And I want the city to ... just feel safe right now. There is no one at large."
Casper is Wyoming's second-largest city with a population of about 56,000. Wyoming residents refer to it as the "Oil City" because it's a hub for the state's oil industry.
The attack at the two-year community college in Casper occurred while class was in session.
Walsh said authorities evacuated all students and staff from the science building.
The college sent out a campus-wide alert via text message and email within two minutes of receiving word of the attack, school spokesman Rich Fujita said.
The lockdown ended about two hours later after school officials received word police were no longer searching for a suspect, Fujita said.
Classes were to resume on Monday.
There are fewer classes on Friday than any other day of the week at Casper College, so only between 1,500 and 2,000 of the college's 5,000 students were there, he said.