Boston to mark 4th anniversary of deadly marathon bombing

A skateboarder jumps over the newly applied Boston Marathon finish line on Boylston St., Thursday, April 13, 2017, in Boston. The finish line is made from an adhesive decal that covers a painted version that is left in place throughout the year. The 121st Boston Marathon is to be run Monday, April 17. (AP Photo/Steven Senne) (The Associated Press)

Family members of Boston Marathon bombing victim Martin Richard, from left, Denise, Jane, Bill and Henry Richard, arrive to place a wreath during a ceremony on the fourth anniversary of the bombings, Saturday, April 15, 2017, in Boston. (AP Photo/Michael Dwyer) (The Associated Press)

Family members of Boston Marathon bombing victim Martin Richard and Lu Lingzhi walk down Boylston Street towards the finish line after laying a wreath during a ceremony on the fourth anniversary of the bombings, Saturday, April 15, 2017, in Boston. (AP Photo/Michael Dwyer) (The Associated Press)

Bostonians are marking the fourth anniversary of the deadly Boston Marathon attacks.

Quiet remembrances have been planned Saturday to remember the victims. Three spectators were killed and more than 260 others wounded when two bombs planted near the finish line exploded on April 15, 2013, spraying shrapnel into the crowds.

A Massachusetts Institute of Technology police officer also was killed later while struggling with the bombers as they tried to steal his gun.

Bomber Tamerlan Tsarnaev was killed in an ensuing standoff with police. His younger brother, Dzhokhar Tsarnaev, was convicted on federal charges and sentenced to death.

The attacks have inspired several movies, including the Mark Wahlberg film "Patriots Day."

On the eve of the anniversary, volunteers planted thousands of daffodils along the marathon course in solidarity.