A trailer containing U.S. Postal Service mail bound for the Kenai Peninsula caught fire Tuesday morning — destroying the trailer and its contents, according to a USPS press release. The driver of the semi-tractor truck hauling the trailer escaped with no injuries. The cause of the fire is unknown but under investigation.

A contract truck left the U.S. Anchorage Processing and Distribution Center on Tuesday morning, and the trailer caught fire near Mile 38 Seward Highway just north of the Seward-Sterling Highway intersection — the “Y” — near Tern Lake.

The truck hauled mail for these towns and postal code areas: Kasilof 99610, Clam Gulch 99568, Ninilchik 99639, Anchor Point 99556, Homer 99603, Fritz Creek 99603, Halibut Cove 99603, Nanwalek 99603, Nikolaevsk 99556, Port Graham 99603, Nikiski 99635 and Seldovia 99633.

Affected customers will be sent a letter.

“Customers expecting mail and packages in these areas who think their mail may have been impacted should call the Postal Service Call Center at 1-800-275-8777 for further assistance,” according to the press release. “If a package was insured, a claim can be filed online at www.usps.com/insuranceclaims/online/welcome.htm.”

“The Postal Service regrets this unfortunate situation and any inconvenience it may cause,” USPS wrote in a copy of the letter attached to the press release. “If you are questioned by a mailer, creditor or correspondent regarding mail or packages that may have been destroyed in this fire, feel free to use this letter as explanation.”

For packages or other mail with tracking numbers, USPS should be able to identify lost mail by Wednesday, said James Boxrud, a USPS spokesperson.

“It doesn’t happen very often,” he said of the fire. “This is my first time it’s happened with a whole truck and a whole city.”

Some postal customers receive daily emails informing them of mail or packages scheduled for delivery through the Informed Delivery service at https://faq.usps.com/s/article/Informed-Delivery-The-Basics. Because mail is scanned during various steps in the process, and may not have been scanned before it left Anchorage, that service may not be useful in determining if mail was lost in the fire, Boxrud said.

Reach Michael Armstrong at marmstrong@homernews.com.