Heavy Fighting(Continued from Page 1)eluding four women, already had been found and they told Interrogators 45 other Viet Congagents had entered the city.A 2 4-hour curfew was put on the city of 300,000 Sunday but was reduced today to 12 hours, from 6 p.m. to 6 a.m.The heaviest battle raged 15 miles south of the city, around a district headquarters town, Dien Ban. South Vietnamese infantrymen and militiamen, and U.S. helicopter gunships and artillery were credited with killing 253 enemy soldiers in a 24-hour fight that ended early today.It began at 3 a.m. Sunday when about 500 North Vietnamese troops attacked the headquarters area of the South Vietnamese 51st Regiment’s 2nd Battalion. Assault forces equipped with flamethrowers got within 50 yards of the command post before they were repulsed.The South Vietnamese troops pursued the enemy soldiers while militia men closed in from another direction, trapping the enemy.