LOS ANGELES (CBSLA) – Big rigs were spotted lining up – and slowing down – along freeways in Southern California Friday in an apparent protest over frustration with coronavirus relief efforts.

What appeared to be at least two dozens slowed down traffic along the 10 Freeway near downtown L.A., while a similar scenario played out on the 10 Freeway in Baldwin Park.

Truckers protesting on the 10 Fwy in Downtown LA blocking traffic. pic.twitter.com/3lUjf2n8Nc — Ed-grr (@idntfd) April 24, 2020

@SGVCityWatch @E_SGVScanner it looks like some sort of trucker protest. The lead truck was driving approximately 10 miles an hour in the number for Lane with a sign that read "stop booking cheap loads." 10 West passing Francisquito pic.twitter.com/U8O3STklui — Ratfink Renegade (@LoonOnTheGrass) April 24, 2020

Another protest was reported in Arizona, where truckers circled the state capitol building.

Truckers circling Arizona State Capital protesting long work hours because of Coronavirus Pandemic #COVID19 #TruckDriver #fox10phoenix pic.twitter.com/BMjnHEJRUd — Rick Davis (@rdavisfox10) April 24, 2020

While there wasn’t any immediate information on what was behind the protests, the Owner-Operator Independent Drivers Association (OOIDA) sent a letter last week to Congress expressing frustration with the Payroll Protection Program and other efforts by the Small Business Administration to help businesses stay afloat during the pandemic.

The letter read in part: “We are currently receiving several hundred calls daily from drivers who are unable to buy essential supplies to protect themselves from COVID-19. Basic items like paper towels, hand sanitizer, and disinfectant wipes are nearly impossible to find right now. The irony is that truckers are hauling these supplies but they are unable to actually buy them.”

The group previously warned if the nation’s truck drivers become ill in large numbers, the U.S. supply chain could be at risk.