In the first incident, a private bus hit the rear of a truck in Dhorimanna area, killing Prakash Rawal (45) and Alka Ben (35), who were going on a vacation, with other passengers in the bus, to Jaisalmer, investigating officer Rupa Ram said.
The bodies have been kept in a mortuary for post mortem.
"A case has been lodged against the bus driver," Ram said.
The other accident occurred in Goluwala police station area when a state transport bus collided head-on with a trailer, killing bus conductor Raj Kumar (28) and the trailer's cleaner Gulab Singh (35).
"Those injured are undergoing treatment at a government hospital in Sriganganagar and the bodies are at a mortuary of a local hospital," a police official said.
No case has been registered yet, he said.