The first round of civil violence flared in 1983 when the killing of 13 soldiers of the Sri Lanka Army, sparked anti-Tamil pogroms—the Black July riots—in which approximately 3000 Tamils were killed. The riots only aided in the deterioration of the ethnic relations. Militant factions, including the LTTE, at this time recruited in large numbers and continued building on popular Tamil dissent and stepped up the guerrilla war. By May 1985, the guerrillas were strong enough to launch an attack on Anuradhapura, attacking the Bodhi Tree shrine–a sacred site for Buddhist Sinhalese–followed by a rampage through the town. At least 150 civilians died in the hour-long attack.