Massachusetts State Police and other agencies were searching on Monday for a missing jet skier who collided with a boat on the Connecticut River in Northampton.

The collision happened at about 7 p.m. on Sunday. The two boat occupants were rescued by Massachusetts Environmental Police officers, and were transported to Baystate Medical Center in Springfield.

Police searched on the Connecticut River until around midnight, but did not find the missing jet skier.

“Search teams are back on station today,” a Massachusetts State Police spokesperson said on Monday. “Troopers and Officers are deploying side-scan sonar equipment, which feeds a sonar image of the water column and river bottom back to a monitor on the boats.

“If any anomalies or objects are detected by the sonar, divers will enter the water to investigate further,” the spokesperson added.

The missing jet skier is believed to be a 51-year-old man, but final confirmation has not been made.