Four persons were killed and two others injured when their car rammed into a tree in the district on Monday morning, police said.
The incident occurred near Jasrasar village when the victims, hailing from Haryana, were on their way to Mukam in Bikaner.
The driver lost control over the vehicle when a cow suddenly came in front of the car and it rammed into the tree, police said.
They were rushed to PMB government hospital where three were declared dead on arrival and one succumbed to injuries during treatment, the police added.