Despite, or even because of, efforts to put out the fire, it reached the fertilizer, and at 9:12 a.m. detonated it.
The explosion killed everyone on board as well as the dockworkers instantly, including 28 of the 29 volunteer firefighters, launched the ship's 1.5 ton anchor two miles, threw a nearby ship clear out of the water, and was heard as far away as 150 miles, though some survivors had been as close as 70 feet to the docks. Two sightseeing planes were forced out of the sky. Most people killed in the disaster were not in the blast radius but died as a result of the debris, or, in the case of the Monsanto Corporation chemical storage facility that was struck by flaming debris killing 234 out of its 574 employees, secondary explosions touched off by the debris. Oil refineries were hit and 500 homes were destroyed by shrapnel traveling at supersonic speeds. The Grandcamp explosion pushed a sister ship, the High Flyer, also carrying an explosive cargo, completely across the harbor. Once the vessel came to rest her crew abandoned ship, but failed to notice they had a fire of their own which burned all night before exploding on the 17th, killing two.
Out of at least 581 people killed in the explosion, 113 were never found, and of those that were, 63 of the bodies were unidentifiable. It is possible that a number of transient individuals were killed in the explosion as well such as tourists, the homeless, and illegal immigrants. 1,784 people were checked into 21 nearby hospitals out of the 5,000+ people who were injured. The explosion caused $100,000,000 in damages. The disaster made national news, and donation offers came from all over the country. Mafia boss Sam Maceo set up one of the largest fundraising efforts, organizing a benefit featuring entertainers such as Phil Harris, Frank Sinatra and Ann Sheridan. Both the Grandcamp's anchor and the High Flyer's propeller now sit in a memorial park.