The man believed to be responsible for the Christmas Day bombing that tore through downtown Nashville blew himself up in the explosion, and appears to have acted alone, federal officials said Sunday.

Investigators used DNA and other evidence to link the man, identified as Anthony Quinn Warner, to the mysterious explosion but said they have not determined a motive. Officials have received hundreds of tips and leads, but have concluded that no one other than Warner is believed to have been involved in the early morning explosion that damaged dozens of buildings.

“Nashville is considered safe,” said Metro Nashville Police Chief John Drake .“There are no known threats against this city.”