Two bicyclists riding in a large group were killed and two others injured — one critically — in a crash Thursday when they were struck by a work truck on the northwest side, sheriff's authorities said.

The bicyclists were members of Santa Fe Seniors on Bikes from New Mexico, said David Gunter, a Santa Fe cyclist, in an interview Thursday night. 

The 10 bicyclists were southbound on North La Cañada Drive and had stopped for a red light at West Hardy/Overton Road, said Deputy Ryan Inglett, a sheriff's spokesman. 

A pickup truck that was also southbound struck at least four of the cyclists at about 12:30 p.m., Inglett said.

One rider died at the scene, a second was taken to Banner-University Medical Center and died there. A third bicyclist suffered critical injuries and the fourth had non-life-threatening injuries, he said.

The names of the riders were not released pending family notification.

All the bicyclists were in the bike lane when they were struck, he said.

The driver of the truck, who worked for a roofing company, was arrested on suspicion of impaired driving. He is in custody and was being questioned Thursday afternoon. His name was not immediately released.

David Gunter, a bicyclist with Santa Fe Road Riders, said the bicyclists struck by the pickup were members of Santa Fe Seniors on Bikes. Gunter said some of the bicyclists also travel with Santa Fe Road Riders.

Members of Santa Fe Seniors on Bikes "planned to visit Tucson. Most of the riders are retired and travel to warmer places to ride in the winter months," said Gunter.

The news of the crash and deaths is spreading among members and it is "hitting people pretty hard," said Gunter of the bicycle club for riders age 50 and older.  

Contact reporter Carmen Duarte at cduarte@tucson.com or 573-4104. Twitter: @cduartestar