A bedroom door-sized chunk of rockwork plaster broke off from the faux mountainside of the Matterhorn Bobsleds roller coaster at Disneyland and forced the closure of one side of the attraction.

Disneyland officials said the rockwork broke loose early Thursday morning while the Anaheim theme park was closed.

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“During overnight maintenance, a portion of decorative rockwork was found to be in need of repair, which we are working quickly to make,” Disneyland officials said in a statement.

A graveyard shift maintenance crew discovered the fallen rockwork. Nobody was injured. The plaster chunk did not fall on the coaster track.

The Matterhorn coaster has two separate tracks. The side of the attraction where the rockwork broke loose was closed on Thursday. The other side remained operational.