As one gate closure extends until Tuesday, and another pops up in Los Angeles, industry observers warned the sudden closures could lead to congestion and other fallout.

Two of the Port of Long Beach’s largest container terminals closed truck gates for the day shift on Monday, raising alarm bells.

Total Terminals International and Pacific Container Terminal were closed as of Monday afternoon, according to Lee Peterson, a spokesperson for the Port of Long Beach. The port’s other four terminals remained open.

“Operators of those terminals made the decision to close based on operational needs, and will reopen for the evening shift,” Executive Director Mario Cordero said in a statement.

The two terminals had alerted truckers of plans to shut down access to truck gates on Monday ahead of schedule, Harbor Trucking Association CEO Matt Schrap told Supply Chain Dive. But the decisions still limit truckers’ ability to effectively plan, even though night-side gates are open.

Pacific Container Terminals had alerted truckers of a June 5 shift closure as of last week, Schrap said. But on Monday, the company suddenly announced it would also be closed for the day shift on Tuesday, according to a broadcast email shared with Supply Chain Dive.

Similarly, TTI gave truckers one day notice for its closure. The terminal updated its schedule on Sunday to indicate that truck gates would be closed for Monday’s day shift, which typically operates from 7 a.m. to 5 p.m. Pacific Standard Time.

The sudden closures raised concern from some industry observers, who warned congestion or other issues could follow if disruptions were to continue throughout the week. The news came days after an ongoing labor dispute led to snarled terminal operations across several West Coast ports Friday.

However, it was not clear on Monday whether the truck gate closures at TTI and PCT were directly related to the ongoing contract negotiations between the International Longshore and Warehouse Union and the Pacific Maritime Association.

The terminal was closed “due to operational needs,” port spokesperson Lee Peterson told Supply Chain Dive in a Sunday night email. “They have caught up on their cargo and they won’t need to work a vessel tomorrow.

The terminal currently has three vessels, which arrived over the weekend but are not expected to depart until at least June 8. Dispatch records show longshore gangs, or groups of workers, were assigned to the three ships on Monday morning, but it will take several more days to finish work on the ship. However, all goods should already be in the terminal, since the cutoff date for truckers to bring containers destined for the ship has already passed.

For truckers, though, any change to truck gate schedules can cause ripple effects.