DES MOINES, Iowa (AP) -- Authorities say seven people have been killed - including two teenage sisters - on Iowa roads as a winter storm swept the state Monday, leading to dozens of crashes and a 50- to 70-car pileup near Ames.

The Des Moines Register reports that 17-year-old Avery Arneson and 13-year-old Aiden Arneson, sisters from Decorah, died a two-vehicle crash around 8:30 a.m. Monday on a county road in northeast Iowa. Four other teens were injured and hospitalized in that crash.

In Cedar Rapids, two men died in a crash on Interstate 380. Killed were 24-year-old Jacolby Jesse Burks, of Cedar Rapids, and 21-year-old Devion Martel Luster, of Dixon, Illinois.

One person died and several people were critically injured in the pileup that closed Interstate 35 near Ames.

On I-80, police say a person was killed in a crash east of Grinnell around 1:20 p.m., and another person died and two others were injured at 1:40 p.m. near Durant.