Woodbury police have arrested two juveniles suspected of making shooting threats on social media Tuesday and Friday against East Ridge High School, adding to the number of Minnesota school districts that have responded to alleged threats this week.

According to city officials, Woodbury police and the FBI examined several social media posts on Instagram and Snapchat, as well as text messages. "Using computer forensics, we validated the sources of the messages, identified who created the content, and located them to determine if they had the intent and means to carry out any threats," the city said in a news release late Friday.

In both cases, it said, "it was determined that the subjects did not have the intent or the means" to carry out the attacks. However, the two juveniles allegedly involved were arrested and will face charges.

"Any kind of threat, especially after what happened in Florida, we're going to take very seriously," said Woodbury District spokeswoman Cassondra Knudson.

The Woodbury instances are just two among a string of reported threats to schools and references to shootings made across the Twin Cities.

Police in St. Francis arrested a 17-year-old student Friday in connection with a threat that led to school closings.

"This was a verbal threat that was taken seriously by law enforcement and St. Francis area schools. … At this time there are no other known threats toward any St. Francis area schools," St. Francis police said in a news release.

Earlier in the day, St. Francis High School said on its website, "To ensure safety of all our students and staff, the decision was made to cancel school for today. … All buildings will be closed and staff are directed to stay home." Early childhood programs, community education classes and all after-school and evening activities also were canceled, the district said.

The notice did not specify the nature of the threat, but police said the student who made it is believed to have targeted the Crossroads School and Vocational Center, a school for students with special needs.

It was the second threat this week in St. Francis, a district of about 4,800 students in Anoka County. On Feb. 15, the district investigated an alleged threat made by a St. Francis High School student. Police determined the threat was not credible, but extra police were sent to the school on Feb. 16.

A bevy of threats

Friday's closure in St. Francis came a day after a juvenile student in Orono was charged with making threats on social media. The threat forced buildings in the west metro district to go on lockdown Wednesday.

In Aitkin County, schools in Hill City closed Thursday because of a threat circulating on social media. Two girls, ages 15 and 13, were arrested Thursday afternoon on suspicion of having made terroristic threats, according to the Sheriff's Office, which added that there was no known plan to carry out the acts. Both girls remain in juvenile detention.

Four other Minnesota schools reported this week that possible threats had been investigated.

In Orono, schools were closed Wednesday after a threat to shoot students appeared on social media. A 17-year-old male student has been arrested and charged in that case.

The Prior Lake School District said it and police investigated Thursday after hearing of concerns about comments made by a student at Hidden Oaks Middle School. The student was arrested in connection with alleged threats toward other students. Authorities declined to release further details.

In Richfield, police and school officials said they were investigating "a school safety concern," adding, "While we have not been able to substantiate the rumor or gather any additional information to consider this a credible rumor, we have taken extra precautions … which is additionally why teachers are allowed to lock doors during instruction."

In Blaine, police received several reports of a threat people had seen on social media referencing "bhs." Blaine police said in a news release Thursday that the screen shot was from Belen, N.M., and had no relation to Blaine.

miguel.otarola@startribune.com tim.harlow@startribune.com