At least 300 civilians were wounded and scores feared killed by Sri Lankan army artillery shells fired into a designated "safe zone" for ethnic Tamils trapped by fighting between the military and Tamil rebels, a health official alleged Tuesday. The shelling comes as the rebels continue to fall back, pulling their forces and civilians into the last remaining areas of dense jungle still under their control and leaving behind ghost towns. TamilNet, a pro-rebel Web site, said the shelling killed more than 300 civilians on Monday. The military denied firing into the zone. The health official, speaking on condition of anonymity for fear of reprisals from the government, said hundreds of wounded had reached nearby hospitals, but it remained difficult to obtain a full account of the casualty toll in the 35-square-kilometer safe zone near Mullaittivu.