PORT HURON (AP) — U.S. border officials say they have seized ancient Egyptian mummy linens during enforcement operations at the Blue Water Bridge that connects Michigan with the Canadian province of Ontario.

The U.S. Customs and Border Protection announced Wednesday officers seized a package of five jars of containing the artifacts found May 25 on a Canadian mail truck. The truck had been selected for examination at a nearby station in Marysville, Michigan.

Officials say they worked with a Washington-based archaeological organization and determined the artifacts are believed to be from the Ptolemaic Dynasty from 305-30 B.C. Their removal from Egypt appears to be a violation of federal law.

Authorities say they plan to return the artifacts in the near future and are working to determine who is criminally responsible.