Representatives of the Islamic Community Center of Des Plaines plan to file a complaint today against a man wearing a backpack who they say entered the mosque about 10:30 a.m. Wednesday, made a threat and left.
A short time later, the man entered Des Plaines City Hall and created a disturbance in the city clerk's office, said Des Plaines Police Chief William Kushner.
Officers interviewed the man, who is known to police and city employees, Kushner said. The man was not arrested but was taken for evaluation to Advocate Lutheran General Hospital in Park Ridge, where he remains, Kushner said.
"He is not a threat," Kushner said.
According to Ahmed Rehab, executive director of Chicago's Council on American-Islamic Relations, the man entered the mosque and told onlookers, "Everything will go boom" on Friday.
During a news conference at the mosque Thursday, Rehab called for further investigation and said the incident led officials at the mosque to cancel classes on Thursday and Friday.
"We don't want to cause more alarm," Rehab said. Nevertheless, he called for a "full investigation ... and responsible vetting of an actual threat that was actually made."
Children were in the building at the time, but none came into contact with the man. About 100 children receive religious instruction at the community center, which opened in 2005.
About 1,000 people attend Friday worship services at the mosque, said Mumtaz Khan, a member of the congregation, which he said numbers about 2,000 families.
Asked why mosque leaders did not file a complaint immediately, Rehab said police told them not to worry and that the man was harmless.
The mosque has not received threats before, according to its leaders.
The mosque has received support from police, city officials and community organizations, said Bassam Osman, chairman of Council of Islamic Organizations of Greater Chicago.
"We thank them and appreciate their solidarity with us," Osman said.
Rehab said his organization will work with local law enforcement and congregation members to increase security at the mosque.