- Of the 13 injured, four are in serious condition
- Nepalis are returning to work after a weeklong festival
- Rescue efforts are going on
A bus plunged into a river in eastern Nepal on Thursday, killing at least 40 people, authorities said.
Thirteen others were injured, four of them seriously, according to police spokesman Binod Singh in Kathmandu.
Nepalis are returning to work after a weeklong annual Dashain festival .
The accident may have been a result of overcrowding, the spokesman said.
Rescue efforts are going on at the site in Sindhuli district about 100 kilometers (60 miles) southeast of Kathmandu.
Road accidents are common in the nation because of poor roads, overcrowding, old buses and inexperienced drivers.