DENVER (KDVR) — A Denver high school and law enforcement are being praised for a quick response after a call into police dispatch about a possible threat.

The call came in just before 2 p.m. Monday about a potential active shooter threat — later determined to be unfounded — at Denver East High School. Students Grace Fuller and Farrah Nakamura were among those who heard the alert.

“We got an announcement on the loudspeaker that we were on lockdown, but they didn’t say if it was a drill or not,” Nokamura said.

The lockdown came less than a couple of weeks after a shooting on East Colfax Avenue nearby put the campus on alert. Students said they had a security drill as recently as Friday, but on Monday, they were faced with the real thing.

“We were in our classroom. We had to lock our doors and the police came to each classroom,” Fuller said. The rallying point for students was the football field.

According to authorities, about 90 minutes later, the search of the school was completed. No threat was found.

Classes will resume a normal schedule on Tuesday.