Four people are dead after a gunman opened fire at a hotel bar near near a university campus in Pennsylvania, killing two men and wounding a woman before turning the gun on himself.

State College Police Chief John Gardner said they are still trying to determine why Jordan Witmer, 21, of Bellefonte, reportedly in the military, opened fire inside a bar, shooting the two men he apparently didn’t know.

The Centre Daily Times reported Witmer then shot and wounded Nicole Abrino, his former girlfriend.

Police were called to PJ Harrigan’s Bar and Grill in State College, about three kilometres from Penn State’s campus on Friday night (Thursday local time).

Penn State students took to Twitter to voice their anger that there was “an active shooter” on the streets and Penn State University Police had failed to send out an alert.

Brae Sullivan posted: “There was an active shooter in state college and penn state university police did not and STILL have not notified any of the students about it. absolutey ABSURD that i had to find out my information from GROUPME”.

my brother is literally staying in the hotel that’s part of the active shooting in state college rn and you know what this man does… snapchats me to tell me about it and says “i have a gun too it’s okay”🙄

— Kimmy Harker (@Kimmy_Harker) January 25, 2019

Dean Beachy, 62, of Millersburg, Ohio, died at the scene, and Beachy’s 19-year-old son Steven Beachy died at a hospital.

Ms Abrino was shot in the chest and remains at a Pittsburgh hospital.

Witmer then fled the bar, crashed his vehicle and broke into a home by shooting out a sliding glass door, Police Chief Gardner said.

Inside, he fatally shot homeowner George McCormick, 83, before turning the gun on himself. Mr McCormick’s distraught 80-year-old wife barricaded herself in a room and called 911.

There was no relationship between Witmer and Mr McCormick, and officials believe he chose the home at random, police said.

There was never any threat to Penn State or its students, he added.

They are still gathering information about the shooter, whom he described as being in the military.

Family members told WNEP-TV that Dean Beachy was an auctioneer and that he and his son were in State College for a horse auction.

-with agencies