MIT Police Officer Sean Collier, 26, of Somerville, was killed Thursday.

MIT Police Officer Sean Collier, 26, of Somerville, was killed Thursday.

Vice President Joe Biden, state and federal officials and between 5,000 and 7,000 law enforcement personnel from around the country are headed to Wednesday’s memorial service for MIT campus police officer Sean Collier, 26, who was shot to death Thursday.

City Manager Robert W. Healy announced Biden’s participation Monday at a City Council meeting. The vice president was last here in February for a $10,000-per-seat fundraiser lunch for New England Women for Change.

This will be a far more somber visit. President Barack Obama has already spoken about Collier, saying, “He was just 26 years old. And as his family has said, he died bravely in the line of duty, doing what he committed his life to doing – serving and protecting others. So we’re grateful to him.”

Suspected killers Tamerlan Tsarnaev, 26, and younger brother Dzhokhar A. Tsarnaev, 19, of Norfolk Street in Cambridge, are also identified as the likely culprits behind the bombing of the Boston Marathon on April 15.

In addition to injuring 176, that bombing killed three people, including 8-year-old Martin Richard of Dorchester; Krystle M. Campbell, 29, a graduate of Medford High with the Class of 2001, manager at Jimmy’s Steak House in Arlington and before that a manager with Jasper White’s Summer Shack Restaurants; and Lu Lingzi, a Boston University graduate student from Shenyang in northeastern China.

The killing of Collier, a Somerville resident, has been called an ambush. The affable, devoted officer never got the chance to unholster his firearm before he was killed with six gangland style shots, five to the chest and one to the head.

The Tsarnaevs were hunted in a massive police effort that led to Watertown and stretched long into Friday evening. Tamerlan was killed during a car chase and shootout with police. Dzhokhar, a student at the University of Massachusetts at Dartmouth, was taken into custody and hospitalized.

During the hunt, MBTA Transit Police Officer Richard Donohue Jr., of Woburn, was critically wounded and taken to Mount Auburn Hospital for lifesaving surgery. Donohue and Collier were friends and classmates at a police academy.

The noon ceremony for Collier at Briggs Field at the Massachusetts Institute of Technology is expected to draw some 10,000 people, according to university officials, and the Cambridge Police Department is planning for traffic disruptions.

The Wednesday memorial service will closed the following roads, police said:

bullet-gray-smallVassar Street between Audrey Street and Massachusetts Avenue, starting at 6 a.m.

bullet-gray-smallMassachusetts Avenue from Albany Street toward Boston starting at 7 a.m.

bullet-gray-smallThe Massachusetts Avenue Bridge into Cambridge closed beginning at 7 a.m.

bullet-gray-smallMemorial Drive between Massachusetts Avenue and the B.U. Bridge starting at noon.

“These road closures are going to have a major impact on traffic in the city. Police are asking residents to plan ahead, seek alternate routes and use public transportation whenever possible,” a Monday press release said.