The driver had been smoking marijuana, police said.
The sheet-draped corpses dotted the two-lane road near Lamezia Terme, in the Calabrian region. In addition to the eight cyclists killed, four people were injured: two cyclists and the driver and a young boy in the car with him, a police official said.
It was reported that the driver was placed under arrest on charges of multiple homicide. A police spokesman said the man, a Moroccan national, tested positive for marijuana.