1965: "Loc Thuong, Binh Dinh, South Vietnam, September 1965. Mother and children wade across river to escape US bombing." 1966: "Tan Binh, South Vietnam, 24 February 1966. American troops drag the body of a Viet Cong soldier to be buried." 1968: "Saigon, South Vietnam, 1 February 1968. South Vietnam national police chief Nguyen Ngoc Loan executes a suspected Viet Cong member." 1972: "Trangbang, South Vietnam, 8 June 1972. Phan Thi Kim Phuc (center) flees from the scene where South Vietnamese planes have mistakenly dropped napalm." (source: world press photo)
It looks like a chunk of skin is missing from that person in the lower left of the pic, unless that's just an artifact on the film.
Those are napalm burns. The young girl you see running down the road in the nude. Most likey took her cloths off because they were partially on fire. Napalm which is a combination of gasoline,benzine and a few other basic chemicals when combined forms a jelly like substance that,after exploding in a bomb,sticks too and then burns whatever it touches. Its very nasty stuff indeed.
Looks like it may have been artifact on the film. Here's another photo that doesn't show anything on the leg. However, there was a napalm attack on that area when the photo was taken.
The nude girl was Kim Phuc. Here's a webpage about her: http://www.vietnamwar.com/PhanThiKimPhuc.htm And another interpretaton of the event: http://www.warbirdforum.com/vphoto.htm