<p>Thousands were awoken by the blast, but no one was injured or killed because police had cleared the area after receiving an anonymous tip, state television reported.<br /><br />The national bank and insurance agency in the central Syngrou avenu were heavily damaged, eyewitnesses said.<br /><br />Authorities believed leftist groups blamed for attacks against police in recent months were behind the explosion.<br /><br />Since police killed a 15-year-old demonstrator in December 2008, the Greek capital city has been beset by violent protests and multiple bombings against police stations, banks and state agencies.<br /><br /></p>
<p>Thousands were awoken by the blast, but no one was injured or killed because police had cleared the area after receiving an anonymous tip, state television reported.<br /><br />The national bank and insurance agency in the central Syngrou avenu were heavily damaged, eyewitnesses said.<br /><br />Authorities believed leftist groups blamed for attacks against police in recent months were behind the explosion.<br /><br />Since police killed a 15-year-old demonstrator in December 2008, the Greek capital city has been beset by violent protests and multiple bombings against police stations, banks and state agencies.<br /><br /></p>
