UPDATE: 'Black Lives Matter' protesters continue to block I-93 traffic in Milton, arms locked in 1,200-pound cement filled barrels

MILTON - Protesters have chained themselves to barrels in the middle of Interstate 93 northbound, blocking every lane of traffic during Thursday's morning commute.

Massachusetts State Police said the road is shut down at East Milton Square, along with the HOV lane on I-93 southbound at Mystic Avenue in Medford.

Troopers and local police are working to remove the protesters, and traffic is "severely delayed," state police said on Twitter, adding that the barrels weigh 1,200 pounds.

The protest is in support of the "black lives matter" movement, aimed at calling attention to and reducing the number of people of color killed by police officers.

The Associated Press quotes a statement sent by the protesters, saying the demonstration was meant "to confront white complacency in the systemic oppression of black people in Boston."

ABC affiliate WCVB quotes an activist named Katie Sietz: "Today, our nonviolent direct action is meant to expose the reality that Boston is a city where white commuters and students use the city and leave, while Black and Brown communities are targeted by police, exploited, and displaced."

This is a developing story. It will be updated as more information becomes available.

Total arrests from this morning's protest total 29. They caused serious risk to public safety. More info to be released at 11:30. — Mass State Police (@MassStatePolice) January 15, 2015

Protestors with arms chained together inside barrel on Rte 83 Milton pic.twitter.com/ORaUqQ7les — Tim Alben (@TimAlben) January 15, 2015

RIGHT NOW: @MassStatePolice cutting through barrel that is filled with concrete. @NECN pic.twitter.com/n8jdqqT2FJ — Jeff Saperstone NBC10 Boston (@JeffNBCBoston) January 15, 2015

Arrests will be ongoing at any and all locations where individuals have obstructed traffic. — Tim Alben (@TimAlben) January 15, 2015

RIGHT NOW: Two lanes of traffic getting by. Protestors still on 93 north near East Milton Square. @NECN pic.twitter.com/wBRnMDaAXm — Jeff Saperstone NBC10 Boston (@JeffNBCBoston) January 15, 2015

Protestors arrested on 93 in Somerville #7news pic.twitter.com/rQMXv1mXyq — Steve Cooper (@scooperon7) January 15, 2015

Hmm. MT @OnlyInBOS: ALERT: I-93 NB in Milton protesters are sitting on the highway. pic.twitter.com/oMN4U8Mnae — Dustin Fitch (@DustinGFitch) January 15, 2015

Going 2 #BOSTON? 93NB jammed in #QUINCY w/ reports of protesters "chained to barrels" blocking hwy nr Furnace Brook pic.twitter.com/XXgdulAeBz — Heidi Voight (@HeidiVoight) January 15, 2015