LEXINGTON, Mass. -- A historical marker that commemorated the call to arms at the Battle of Lexington in 1775 was stolen late last week, town officials said.

The bronze plaque marked the location of the Old Belfry that was used to sound the alarm on April 19, 1775, at the beginning of the American Revolution.

The Old Belfry was originally built in 1762 and then moved to the Battle Green in 1768. Its bell was used to summon townspeople to worship or warn them of danger.

The plaque reads, "The site of the Old Belfry from which the alarm was rung, April 19, 1775. This tablet was erected by the Lexington Chapter Daughters of the American Revolution 1910."

The plaque was stolen some time between Thursday and Friday. Pieces of the stone that housed the plaque could be seen strewn about the grounds of the Lexington Battle Green Monday.

The copper plaque might have been stolen by thieves seeking to profit from the high price of copper, police said.

Police have now stepped up patrols in the area and said they are checking with copper melting businesses to see if the plaque has been sold.