BOSTON - In the eight days since a pair of explosions tore through the crowd at the storied Boston Marathon, $20 million has been donated to help the wounded and the families of the dead, Boston Mayor Thomas M. Menino announced Tuesday.

The biggest donation was $1 million, Menino said, and the smallest came from "young people doing lemonade stands, $5, $10, it runs the gamut." In all, One Fund Boston has received 50,000 donations from around the world.

"I never imagined after this tragedy last Monday the generosity of the folks," said an emotional Menino. "The business community of Boston especially, but around the world. … Five million dollars was generated by simple clicks of your computer."

Kenneth Feinberg, who administered victims' funds after the terrorist attacks of Sept. 11, 2001, and other disasters, will oversee the fund. On Tuesday, he said that the deadline for applications is June 15, and checks will be cut to the victims and their families by June 30.

"Every time I do this, I say to myself, 'I hope this is the last time,' " Feinberg said during a news conference near the site of the explosions, which killed three and wounded more than 260. In addition, a Massachusetts Institute of Technology police officer was killed when confronted by the bombing suspects. "It is not the last time. Bad things happen to good people in this country.

"I am amazed, in my experience, to see this type of outpouring so quickly in such large amounts after this horrific tragedy," Feinberg said. "One thing I've learned is … never underestimate the charitable impulse of the American people."

But the difficult task that lies ahead is deciding how the money should be divvied up. Feinberg said that, although applicants will need to show documentation of medical or hospital visits, he expects there to be little fraud. The problem will be the great need.

"You do the math. Thank goodness, just four deaths," Feinberg said, referring to the three from the bombings and MIT police officer Sean Collier. "Double amputees. Amputees. People expected in the hospital for weeks and months. The fabulous outpouring so far cannot begin to make all these people whole."

The idea, he said, is to "help those most in need." Which means that the money will be disbursed to those who have been physically injured, rather than people with business or property losses.