Israeli helicopters attacked a "Hamas" training field in Gaza City early Tuesday, killing at least 14 fighters and wounding 30 others in the deadliest air strike on Palestinian fighters in four years of violence. Hamas vowed revenge for Tuesday's air strike. Hours later, Palestinian fighters fired rounds of mortars and homemade rockets at Jewish settlements in the Gaza Strip and Israeli towns bordering the coastal area. One Israeli in the border town of Sderot was lightly wounded in a rocket attack, the Associated Press quoted rescue officials as saying. In Gaza, children stayed home from school Tuesday and shops remained closed in a sign of mourning. Black smoke billowed over the city as students burned tires at spontaneous demonstrations. Mosque loudspeakers amplified excerpts from the Quran and announced that a joint funeral for the dead Palestinian fighters would begin at 1 p.m. (1000 GMT.)