Palestinian gunmen invaded a Gaza hospital this week and killed two Palestinians who had been convicted of collaborating with Israeli authorities. The men, who confessed to helping Israeli forces kill Islamic militants, had been wounded in a grenade attack on the prison where they were being held, and they were recovering in the Palestinian hospital. Five masked gunmen burst into the hospital in broad daylight, racing past hundreds of witnesses, and shot one of the men in the head as he lay in his bed. A few hours later, they assassinated the second man the same way. Hamas claimed responsibility for the murders.