"One explosion occurred near the bus blast site and the second hit the eastern part of the city," said Nasrat Rahimi, a spokesman for the interior ministry.
Casualties were feared, he said.
At least five people were killed and 10 wounded when a bomb attached to the bus carrying government employees went off, officials said earlier.
A witness near the site of the bus blast said a minibus had caught fire and he could see several injured people and bodies.
No militant group claimed responsibility for any of the three blasts.