Zimmerman told them he lost sight of Trayvon and was walking back to his SUV when Trayvon approached him from the left rear, and they exchanged words.
Trayvon asked Zimmerman if he had a problem. Zimmerman said no and reached for his cell phone, he told police. Trayvon then said, "Well, you do now" or something similar and punched Zimmerman in the nose, according to the account he gave police.
Zimmerman fell to the ground and Trayvon got on top of him and began slamming his head into the sidewalk, he told police.
Zimmerman began yelling for help.
Several witnesses heard those cries, and there has been a dispute about whether they came from Zimmerman or Trayvon.
Lawyers for Trayvon's family say it was Trayvon, but police say their evidence indicates it was Zimmerman.
One witness, who has since talked to local television news reporters, told police he saw Zimmerman on the ground with Trayvon on top, pounding him — and was unequivocal that it was Zimmerman who was crying for help.
Zimmerman then shot Trayvon once in the chest at very close range, according to authorities.
When police arrived less than two minutes later, Zimmerman was bleeding from the nose, had a swollen lip and had bloody lacerations to the back of his head.
Paramedics gave him first aid but he said he did not need to go to the hospital. He got medical care the next day.
As George Zimmerman's supporters work to stem the rising tide of public outrage aimed at the neighborhood watchman who shot and killed Florida teenager Trayvon Martin last month, a new picture of the victim—culled from the 17-year-old's Facebook and Twitter accounts and witness testimony—has emerged.
"With a single punch," the Orlando Sentinel, citing police sources, reported Monday, "Trayvon Martin decked the Neighborhood Watch volunteer ... climbed on top of [him] and slammed his head into the sidewalk several times, leaving him bloody and battered."
"That is the account Zimmerman gave police," the paper said, "and much of it has been corroborated by witnesses, authorities say."
Zimmerman's attorney, Craig Sonner, says that Zimmerman acted in self-defense and is not a racist as some have portrayed him.
"I think we need to let the investigation come forward and let all the facts in this case come out," Sonner said on the "Today" show. "I think it's going to tell a different story than the way it's been related and portrayed in the media."
According to a CNN poll released Monday, 73 percent of Americans think police should arrest Zimmerman.
Meanwhile, the difference between the typical teenager Martin's family and supporters say he was and the way he presented himself on social media is the subject of increasing debate.
I wrote this in response to a person who wanted bullys to stop and be nice
I have lived my whole life trying to stop bullies from hurting people. I was bullied as a very young child and as soon as I was able to defend myself I did, I have been blessed with size and strength. Not all people can do that, but speaking up for ones self must be mastered also. Adults, not in fear of physical violence, should also learn to stand up for themself. This builds self esteem and coping skills, the ablity to take a joke, or brush off and insult. In the Cyber world (FuBar) people can practice standing up for ones self and also block delete or change settings. This Cyber World of social networks (FuBar) also, gives would be bullies a chance to "pay back" for the pain they endured. This is a twisted result of low self esteem, be stronger than those and delete them. I encourage all to take charge of your life, have fun here, and make the friends you want to have. Remember FuBar is NOT real life! people here only have the power you give them by careing what is said or done in the Cyber World. I understand wanting this to be reposted but saying that those that don't, "don't have a heart" is wrong too this is a type of peer preasure to guilt people into doing what you say. Your compassion is good enough, you can not force or pressure people in to being good. I hope those that read this teach this one at a time and, we all have more fun on FuBar.