It took about 30 seconds yesterday for four thieves to steal more than $500,000 worth of watches from Boyd's in Center City, police said.

Lt. Frank Vanore said two of the robbers entered the posh men's store, on Chestnut Street near 18th, about 2:15 p.m.

The bandits aimed a silver handgun at a Boyd's security guard's head, then sprayed the guard and another employee in the face with pepper spray, said Capt. Sharon Seaborough, of Central Detectives.

While a handful of customers cowered on the floor, two more crooks dashed into the store and smashed a pair of display cases with hammers, Seaborough said.

Their prize: 16 watches, made by designer manufacturers Harry Winston and Audemars Piguet.

The crooks fled the store and got away on congested Chestnut Street.

Seaborough said the quartet apparently drove their dark-colored, four-door sedan through Boyd's parking lot on Chestnut to Ranstead Street.

The two security guards did not need to be hospitalized. No other injuries were reported.

Seaborough said tipsters can contact Central Detectives at 215-686-3047.

Despite the robbery, the store hosted a film crew last night as planned, said Michelle Carchedi, Boyd's creative director.

The crew was shooting scenes for a comedy film, "The Best and the Brightest," starring Neil Patrick Harris and Bonnie Somerville, and is using Philly locations as stand-ins for New York City, Carchedi said. *