In two separate cases Sunday, pedestrians were left with serious injuries after drivers struck them then sped away.

According to the San Francisco Police Department, it was 1:35 a.m. Sunday when a 68-year-old woman was struck by a driver as she walked north across Geary Boulevard at Gough Street.

The white, four-door sedan that struck her was last seen racing south down Gough Street, police say. As of the morning, the driver is still at large.

According to a witness to the collision who emailed SFist after this report was published:

I was there when the 68 year old woman was struck. In fact, I called the ambulance. It would be worth noting in your article that the driver’s side view mirror was ripped off when the woman was struck. The mirror was left at the scene along with a part of the grill. The car was definitely a white Toyota Avalon that struck the woman. I thought this information would be crucial for readers to keep an eye out for the vehicle.

The driver's victim was left with severe head trauma, according to SFPD. She was transported to San Francisco General Hospital and remains in critical condition.

Then Sunday at 10:45 p.m., SFPD officers discovered a 31-year-old man lying unconscious near San Jose Avenue and Rice Street, the victim of the second hit-and-run that day.

Police say that they found debris at the scene that suggests that a dark-colored Ford pickup is the suspect vehicle. The impact with the pedestrian, police say, damaged the truck's front headlight on the driver's side.

The victim in that collision also suffered life-threatening injuries, police say, and joined Sunday's earlier victim at SF General for treatment of his wounds.

Police are eager, as you can imagine, to find both of the drivers in these cases. If you know anything, please call SFPD's anonymous tip line at 415-575-4444 or text them a tip at TIP411 with "SFPD" in the message.