Police took into custody one person who was injured and may also have later died, following the attack that happened just before 9 am at Casper College, school spokesman Rich Fujita said.
Authorities were searching the campus for any additional suspects, Fujita said.
"They are reasonably certain that the one and only suspect is in custody, but they told us they can't be 100 per cent certain there is not a second suspect," he said.
The campus was locked down and students were advised to stay where they were until police gave the all clear.
Fujita said he had no additional information, including how the attack happened, what type of weapons may have been used, or who was killed.
Casper police said they couldn't provide information because all of their officers were at the scene. The Wyoming Highway Patrol was helping to direct traffic at the college, but a patrol spokesman said he had no information about what happened.
Casper College is a two-year community college in Wyoming's second-largest city. Casper with a population of 56,000, is about 250 miles northwest of Denver.
Wyoming residents refer to Casper as the "Oil City" because it's a hub for the state's small oil industry. The city is flanked to the south by Casper Mountain, scene of a massive wildfire in September that burned more than 24 square miles of forest and meadows and destroyed 37 homes and cabins.