LOS ANGELES (AP) — Thieves have been raiding cargo containers aboard trains nearing downtown Los Angeles for months, taking packages belonging to people across the U.S. and leaving the tracks blanketed with discarded boxes.

The packages are from retailers including Amazon, REI and others, CBSLA reported Thursday. The sea of debris left behind includes items that the thieves apparently didn’t think were valuable enough to take.

While CBSLA cameras were on the scene, one person was spotted running off with a container used to hold small packages, and a Union Pacific railroad police officer was spotted pursuing two other people who were apparently going through packages.

The scene was the same in November, when NBC4 showed thousands of boxes discarded along the tracks lined with homeless encampments northeast of downtown in the Lincoln Park area.

Passing trains carried containers with doors wide open and packages tumbling out, NBC4 reported. Video showed two men, one holding what looked like bolt cutters, walking along the tracks, the station said.

Union Pacific said in a statement to CBSLA that the railroad was concerned about increased cargo thefts in California.

“We have increased the number of Union Pacific special agents on patrol, and we have utilized and explored additional technologies to help us combat this criminal activity. We also will continue to work with our local law enforcement partners and elected leaders,” the railroad said.

Amazon said it was directing inquiries to police. The United Parcel Service, UPS, declined to comment on investigations into the cargo thefts but said it was cooperating with authorities.

“The safety of our customers’ goods and our employees is our highest priority,” UPS said in a statement.

Luis Rosas, who makes about $20 an hour working for a company subcontracted by Union Pacific to salvage items from the tracks in the Los Angeles area, says he’s encountered the brazen thieves in action before. Using bolt cutters, they break locks on the containers and load up vans or trucks with the stolen merchandise.

Rosas has been doing this work almost daily for about six months and while he’s been told not engage in confrontations, he still feels afraid.

“They don’t even run off anymore. They do it right in front of us,” he told The Associated Press on Friday, wearing a bright yellow vest before he headed to work to pick up car tires along the tracks. “At first I was shocked. I was amazed by it.”