More than 24 hours after it began, Minneapolis' school lockdown ended Thursday after police determined there was no threat to the city's 32,000 students.

The Minneapolis threat was telephoned about 7:30 a.m. Wednesday to the city's 311 information line. The caller said that someone had warned on a social networking site that "a male will be coming to a Minneapolis school, shoot up the school and then shoot himself," said Minneapolis police spokesman Sgt. Jesse Garcia.

School officials imposed a Code Yellow, locking outside doors and taking other security precautions at all 60 of the district's schools.

Meanwhile, Minneapolis and St. Paul police worked together on an investigation because a similar threat caused a lockdown at St. Paul's Cretin-Derham Hall on Wednesday. Though the Minneapolis lockdown continued into Thursday, school officials lifted it after police determined that harm to students was unlikely.

"We do not believe there is means for the person who likely posted this to carry out the threat," said St. Paul Police spokesman Sgt. Paul Schnell.

Police learned that the Minneapolis and Cretin-Derham Hall threats were made from a computer in Australia. The Cretin-Derham threat was first noticed by a good Samaritan in the Netherlands, who contacted St. Paul school officials, Schnell said.

Minneapolis school officials said that instruction proceeded as usual during the lockdown. Though school officials didn't have attendance numbers Thursday, a spokesperson said reports indicated there weren't an unusual number of absences.

Police said the investigation would continue with help from federal and international authorities.

"We want to know who did it, why they did it and to make sure it won't happen again," Schnell said. "The reality of the world is that we are dealing with people engaged in criminal behavior sitting behind a keyboard."

Staff writer Mary Lynn Smith contributed to this report.