The source said that all police and special forces units in Berlin have been informed and put on high alert
German media cited local security sources as saying that there was evidence suggesting the arrested suspect was from Afghanistan or Pakistan and entered Germany in February as a refugee.
German newspaper reports police believed there to be multiple injuries, but police couldn't immediately be reached to confirm
Neo-Nazi protestors are strongly against Germany's refugee policy
The explosion occurred at about 8 am (local time) in the western district of Charlottenburg