New London — Police are crediting a detective with stopping a man who appeared to be planning to rob a convenience store Thursday morning.

Detective Keith Crandall was traveling in the area of Bank Street and Ocean Avenue in an unmarked cruiser when he spotted a man wearing dark clothing and a hat and scarf walking on Bank Street near Sam’s convenience store, according to a statement from Deputy Police Chief Peter Reichard.

The man, later identified as 28-year-old Ryan C. O’Donnell of Ashaway, R.I., began to position the scarf over the lower portion of his face, leaving only his eyes exposed, police said. O’Donnell walked past the entrance to the store, looked in both directions and inside the store.

Believing a robbery was about to occur, Crandall drove into the parking lot, got out and identified himself. O’Donnell began to “quickly walk away” but was ordered to stop, and when he moved his hands toward his waistband, he was ordered not to move and was asked if he had any weapons, according to the police statement.

He said he did have a gun. Crandall seized a pellet gun O’Donnell was carrying and charged him with carrying a dangerous weapon. Bond information was not immediately available.