The collision occurred around 9 AM when the bus carrying tourists from West Bengal was going to Netarhat while another bus was heading to Ranchi from Gumla, Sub-divisional police officer Deepak Kumar Pandey said.
He said three persons died on the spot, while nine seriously injured passengers were being sent to Rajendra Institute of Medical Sciences in Ranchi.
The other injured were being treated in the nearby public health centre, he said.