DENVER Police in Denver and Commerce City are investigating two separate fatal crashes involving single vehicles Friday night and early Saturday morning.A man driving a pickup truck northbound on Quebec Parkway near E. 64th Avenue in Commerce City was killed when he was ejected from his vehicle during a rollover crash around 11 p.m. Friday, according to police.Police said the pickup truck driver struck a median and lost control. Following the crash, the truck ended up in a field by the roadway.The identity of the man, who police said was the only occupant in the vehicle, has not been released.In Denver, police are investigating a single-vehicle crash that occurred sometime after midnight Saturday on northbound Santa Fe Drive and Interstate 25.Police said a passenger in the vehicle was declared deceased on scene. No other injuries were reported.The identity of the deceased has not been released.