A human rights group said Israel fired white phosphorous shells indiscriminately over densely populated Gaza, and that this is evidence of war crimes. Human Rights Watch issued a report Wednesday on the use of white phosphorous shells during Israel's three-week operation in Gaza. A common military use of white phosphorous is to obscure the operations of troops in open areas. However, Human Rights Watch said Israel fired these shells repeated over crowded neighborhoods. The group said safer smoke shells were available. The report said civilians suffered and died needlessly, and that senior commanders should be held accountable. The Israeli military had no immediate comment. It has said in the past it is investigating the use of white phosphorous.