PERRY, Iowa [KCCI]— Two separate threats made by students in Perry were found not to be credible, police said Sunday — exactly one month after a deadly school shooting rattled the community.

Perry police said in a news release that the department received numerous reports this weekend from concerned parents and students alleging that a threat was going to occur Monday. Another student posted a photograph on social media “that was also concerning,” authorities said.

Officers investigated both allegations thoroughly and deemed the threats not to be credible. The district is aware of the threats, and officers will continue to be present at all Perry schools.

The threats come one month after a 17-year-old student at Perry High School opened fire in the cafeteria, killing sixth-grader Ahmir Jolliff and wounding seven others before taking his own life. High school principal Dan Marburger died 10 days after being seriously hurt in the Jan. 4 shooting.

Perry High School students returned to class last week for the first time since the shooting. The district said it has taken steps to increase security on campus. The high school is limiting how much time students are allowed in the building: 25 minutes before the start of the day and 15 minutes after the school ends. The district also recently completed an application for a $150,000 grant to help improve school security.