Bulgarian government officials say at least 40 people have been injured, some of them seriously, in a toxic gas attack on a police station in the capital, Sofia.
The Bulgarian Interior Ministry says Sofia's central police office was packed with visitors Friday, when an unidentified man threw a bomb containing a toxic chloride gas into the crowd.
Police immediately evacuated the building, and dozens of people were hospitalized. At least one person was said to be in very serious condition, and four others were listed as critically ill.
The Health Ministry has identified the chemical as a chlorine-based pesticide that is said to have been used in the past as a military-grade tear gas. It was also used in chemical weapons during World War I by both Germany and the Allies. Experts say it can be extremely dangerous when inhaled in large quantities, causing acute lung inflammation. In smaller quantities it causes skin and eye irritation.
Police have arrested one suspect, although there is no word on a possible motive.
The incident has underscored concern in Bulgaria about possible terrorism because of its support for the U.S.-led military operations in Iraq.
Bulgaria has close to 500 troops serving in Iraq near the town of Karbala as part of an international force under Polish command. The area has been the scene of heavy fighting between coalition troops and a local militia this week.
At least five Bulgarian soldiers have been killed and many more wounded since they arrived in Iraq last year.
The gas attack in Sofia occurred early Friday. Officials say, tests later in the day indicated there was no further danger to the public.