William Hart, lead singer and songwriter of Philly R&B/soul legends The Delfonics, died on Thursday (7/14) at age 77. His son Hadi told TMZ that he was having trouble breathing so he was admitted to the Temple University Hospital in Philadelphia, where he passed away due to complications during surgery.

Hart sung in a variety of groups around Philly in the early 1960s before forming The Delfonics in 1965 with his brother Wilbert Hart and Randy Cain. They went on to release such classics as "La-La (Means I Love You)" and "Didn't I (Blow Your Mind This Time)," both of which were re-popularized in the 1990s after the former was used in Spike Lee's Crooklyn and both were used in Quentin Tarantino's film Jackie Brown. Nicholas Cage also sang "La-La" in 2000's The Family Man. Other hit singles written or co-written by William include "Ready or Not Here I Come (Can't Hide from Love)" and "I'm Sorry." The Delfonics have been covered and sampled by a variety of other artists, including The Jackson 5, Aretha Franklin, The Notorious B.I.G., Fugees, Missy Elliott, Three 6 Mafia, and more. They had another resurgence with the release of Adrian Younge Presents the Delfonics in 2013.

Rest in peace, William.