Following reports of an unknown material being delivered by postal service, authorities, including police and fire services, raced to the Masjid Bilal Islamic Centre on Bury Old Road in Prestwich, causing a major emergency response.
To ascertain if the incident was a hoax or a real chemical threat, Greater Manchester Police has opened an inquiry.
According to their statement, the police acknowledged receiving allegations of the material and, working with the Greater Manchester Fire and Rescue Service (GMFRS), evacuated the area as a precaution.
Authorities believe there is no wider risk to the community, and no one has reported feeling ill as a result of the chemical.
