Cretin-Derham Hall was on partial lockdown this morning, after an e-mail threat that said something would happen Wednesday at the Catholic high school in St. Paul.

The school received an e-mail Wednesday morning about a “vague threat on the Internet,” Principal Richard Engler wrote in an e-mail alert to parents.

St. Paul Police Sgt. Paul Schnell said the threat indicated that a shooting would happen in or near the school, according to Minnesota Public Radio. Investigators continued to search for the source of the threat, believing it might have come from outside of the U.S., according to the MPR report.

Police were at Cretin-Derham Hall to investigate, with officers posted at every door, Engler wrote, adding that the school was not “going into full lockdown” and that classes would continue as normal. Students were being kept in their classrooms at all times except during period changes, Engler wrote.

An elementary school also was locked down for a time because it was near Cretin-Derham Hall, according to MPR.

“We are continuing to work with the police department,” Engler wrote to parents. “Our utmost concern is the safety of the students. We are confident that the school is safe and secure.”

All Minneapolis public schools also were in lockdown Wednesday morning after school officials received “unspecified threats,” said Stan Alleyne, communications director for the school district.

Alleyne told MPR that a tip received from law enforcement agencies came from social networking sites. The threat led the school district to begin a “code yellow lockdown,” with students remaining in their classrooms and access to the schools “limited.”

The two threats were not thought to be related.