Seven miners were killed and nine other were injured in an explosion at a mine in eastern Ukraine early Tuesday, officials said.The blast took place at the Pivnichna mine in Ukraine’s mineral-rich Donetsk region. The bodies of the victims were recovered and work at the mine has been suspended, Ukraine’s emergencies ministry said.Ukraine’s coal mines are among the most dangerous in the world.The industry suffers from poor infrastructure and lax safety standards.The cause of the explosion at the state-run Pivnichna mine was being investigated but Ukrainian media blamed it on a gas leak.Three years ago, an explosion in eastern Ukraine left at least 16 people dead.More than 100 miners died in 2007 in an explosion at Zasyadko mine, also in the Donetsk area.