Police could not immediately confirm identities of the deceased.
Officer-in-Charge of Magura Police Station Joynal Abedin said a bus of Shohagh Paribahan collided head-on with a Khulna-bound bus of Chakladar Paribahan at 1:30pm leaving three people dead on the spot.
Another man died after being taken to the hospital, the OC said.
After the accident, the Chakladar Paribahan bus plunged into a roadside ditch as another bus of Highest Paribahan hit it from behind, he said.
Vehicular movement remained suspended for two hours after the accident, the OC said, adding that the injured were admitted to the Sadar Hospital.
Police seized the three vehicles but their drivers are on the run, he added.
Also read: Accidents killed 553 in August
At least 459 people were killed and 618 others injured in 388 road accidents last month, according to a report prepared by Bangladesh Jatri Kalyan Samity.
According to it, motorcycles were responsible for 28.98 percent of the accidents, trucks and covered vans 21.61 percent, buses 16.12 percent, auto-rickshaws 8.74 percent, battery-run rickshaws and easy bikes 9.77 percent, human hauler 7.71 percent and jeep and microbus 7.03 percent.
Also read: 4 of a family among 6 killed in Barishal road crash