Goodyear, Arizona, police chief Santiago Rodriguez said Monday that investigators do not believe the driver of a pickup truck who killed two cyclists and injured 19 others on Saturday morning intentionally plowed into the group. 

The alleged driver, 26-year-old Pedro Quintana-Lujan, was arrested at the scene and charged with two counts of manslaughter, three counts of aggravated assault with a deadly weapon, 18 counts of endangerment, and two counts of accidentally causing serious injury or death by a moving violation. 

A blood test was taken to determine if the driver was impaired, though Rodriguez said it's unclear when investigators will get those results. 

"There is no indication that this was an intentional act or anything other than an isolated incident," Rodriguez said at a press conference on Monday, noting that authorities are just starting their investigation. "There are numerous interviews that we still need to do, inspections, things of that nature."

Quintana-Lujan was on the way to a work site shortly before 8:00 a.m. on Saturday morning when he allegedly plowed into a group of 20 cyclists on Cotton Lane Bridge in the Phoenix suburb of Goodyear. 

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Two cyclists were killed. Karen Malisa, a 61-year-old Goodyear resident, was pronounced dead at the scene. Another cyclist, a 65-year-old man from Michigan, succumbed to his injuries at a local hospital. 

Over a dozen other cyclists were injured and one of them was still in critical condition on Monday afternoon. 

Quintana-Lujan was driving a Ford F-250 at the time of the crash. He is being held on a $250,000 bond. 

Rodriguez urged drivers to be mindful of cyclists when traveling in Goodyear. 

"Vehicles must give bicyclists three feet of clearance," Rodriguez said Monday. "Bicyclists not only have the right to travel the roads, but are treated with the same considerations as any other vehicle on the road."

Fox News' Danielle Wallace contributed to this report.