A group of West Roxbury residents and students from Hampshire College and UMass Amherst briefly blocked construction of a trench up Washington Street for a high-pressure natural-gas pipeline this morning before they were cuffed, put in prisoner wagons and taken down to District E-5 for booking.

It's the third such protest against the pipeline and the largest number of protesters arrested at one time.

Starting shortly after 9 a.m., the 12 separated from about 20 other protesters on the sidewalks and walked to the trench where the 750-psi pipeline will go, on its way from Dedham to a transfer station at Grove and Centre streets, where it will connect to National Grid's local distribution system. Protesters say the pipeline will be a menace to the neighborhood, especially the transfer station.

They held hands and chanted and sang against the pipeline and against Spectra, the company building it, for about 15 minutes. Workers stopped extending the trench from the inbound side to the outbound side of Washington, just past Rockland Towers.

Then, a protest organizer who had just talked to E-5 Captain Joseph Gillespie told them police said they could only continue protesting until a second prisoner wagon showed up to join the one already stationed there. About ten minutes later, it arrived, and Gillespie gave the protesters one last chance to disperse.

When they didn't, an officer got out a cache of plastic cuffs and the protesters were put in them, taken to the wagons, pat frisked and loaded into the wagons to await their ride to the local police station.

As the last of them was put in a wagon and the doors shut, supporters chanted "We'll be back! We'll be back!"

Before the work stoppage: