Seven Waymo robotaxis blocked traffic moving onto the Potrero Avenue 101 on-ramp in San Francisco on Tuesday at 9:30 p.m., according to video of the incident posted to Reddit and confirmation from Waymo.

While routing back to Waymo’s city depot that evening, the first robotaxi in the lineup came across a road closure with traffic cones. The only other path available to the vehicles was to take the freeway, according to a Waymo spokesperson. California regulators recently approved Waymo to operate its autonomous robotaxi service on San Francisco freeways without a human driver, but the company is still only testing on freeways with a human driver in the front seat. Waymo told TechCrunch it is first prioritizing a safe and gradual scale of rider-only freeway operations in Arizona before advancing in California.

After hitting the road closure, the first Waymo vehicle in the lineup then pulled over out of the traffic lane that was blocked by cones, followed by six other Waymo robotaxis. Human-driven cars were then stuck behind some of the robotaxis; a video posted online shows fed-up drivers getting out of their cars to physically move the cones out of the way so they could pass both the road closure and the stalled Waymos.

Waymo told TechCrunch it immediately dispatched its Roadside Assistance team to manually retrieve the vehicles and that the whole event lasted no longer than 30 minutes.

It’s not the first time Waymo vehicles have caused a road blockage, but this is the first documented incident involving a freeway. Cruise, GM’s autonomous vehicle subsidiary, has come under scrutiny for multiple cases of its vehicles malfunctioning and blocking traffic, first responders and public transit. Of course, human drivers block traffic all the time, but city officials and first responders in San Francisco have expressed frustration with both not being able to access and move robotaxis when they’re in the way and not being able to issue traffic citations to the vehicles. In San Francisco, there must be a driver in the car in order to issue a citation.