A motorcyclist crashed his bike on a curve on a street north of the Twin Cities and was killed, authorities said Monday.

The wreck occurred about 6:30 p.m. Sunday about 4 miles northeast of St. Francis, according to the Isanti County Sheriff's Office.

The rider was identified as Tad Demmon, 53, of Isanti. Demmon was taken by air ambulance to a hospital and died there, the Sheriff's Office said.

Demmon was riding west on NW. 249th Avenue, lost control on a curve near Zion Street and rolled into a ditch, the Sheriff's Office added.

Authorities have yet to say whether Demmon was wearing a helmet.