The US embassy in Brussels was evacuated while police investigate a suspect vehicle, officials and police said.
"I can confirm we have been evacuated. There was a suspect vehicle," said Viktor Sidabras, the spokesman for the US mission to the European Union.
Belgian news agency Belga said police closed several main routes out of the city and sealed off a security zone around the embassy
An eyewitness has told local media that there were a dozen worshippers in the mosque when a man attacked with a petrol bomb. An imam died as a result of smake inhalation, and another person was injured. Azzedine Laghmish told Belgium's national broadcaster RTBF:
A man has been taken into custody following an arson attack on a mosque in the Brussels suburb of Anderlecht, police spokeswoman Marie Verbeke told AFP.
An imam has died after an arson attack on a mosque in the Anderlecht district of Brussels in Belgium. Witnesses said a man entered the mosque before throwing a petrol bomb. Initial reports said the imam, 47, died of smoke inhalation, and one other person was injured.