A group of Muslim volunteers will hold a blood drive at the Dana Farber Cancer Institute, at 450 Brookline Ave. in Boston, Wednesday from 9 a.m. to 3 p.m. The drive, a response to the Boston Marathon bombings, will be located inside the cancer institute’s traveling blood donation bus, organizers said. The event is organized by members of Mercy to all Mankind, a small group of Muslims seeking to help the greater community while building relationships between non-Muslims and themselves. People attending the drive are encouraged to write and send handwritten notes to the victims and first responders, organizers said. For more information on the event, visit Facebook.com/Mercytoallmankind.