Kevin Nursick, spokesman for the Connecticut Department of Transportation, said the Mystic Drawbridge was closed to traffic for more than three hours Sunday because of a relatively minor problem.

“Limit switches” that signal whether the sides are properly closed and aligned malfunctioned, he said. Nursick said the sensors sent a message to the bridge operator that something was wrong, so the gates remained closed to traffic.

He said the department now knows the bridge was working, but it didn’t know that at the time. He said the department is sorry people were inconvenienced, but it had to take precautions.

“We take the blame on this, but we take the blame knowing that we did the right thing, because we don’t take chances with safety,” he said.

The switches are being fine-tuned or replaced if needed, he said. The process should be done in about a week, Nursick said.