Chinese fighters, who soon dropped the air-burst devices that descended under parachutes, and detonating just a few hundred meters in front of the lead bombers, resulting in a breakup of the bomber formation followed by furious attacks from the Chinese fighter pilots the best they could with the handicap of the highly challenged performance and firepower of their Polikarpovs, claiming five shot down (two wrecks confirmed) and damaging many others; eight Chinese fighters suffered various degrees of damage while the wreckages of Japanese bombers were found in Shichuxian and Shuangqing with three of the seven-man crew in one of the bombers found alive and taken prisoner. The state-of-the-art new Japanese Mitsubishi A6M Zero fighters were first deployed into combat in course of the Chongqing and Chengdu bombing raids, and received its first baptism of fire in aerial combat on 13 September 1940; 13 Zeroes of the 12th Kokutai led by Lieutenant Saburo Shindo which had escorted 27 G3M bombers on a raid into Chongqing were sent against 34 Chinese fighters: including Polikarpov I-15bis (led by Maj. Louie Yim-qun of the 28th PS) and I-16 (led by Capt. Yang Mengjing of the 24th PS) and other Polikarpov fighters of Maj. Zheng Shaoyu's 4th PG. The battle lasted about half an hour by which point the Chinese were low on fuel and had to break off; with some luck, escaping further contact with the much faster Zeroes. Many of the Polikarpovs were damaged or shot down (the Zero pilots claiming 27 Polikarpovs shot down), with ten pilots killed, and eight wounded, Maj. Zheng Shaoyu and Lt. Gao Youxin managed to drive Zeroes off the tails of other Chinese fighters, with Lt. Gao closing-in to 50 meters (160 ft) of one, and claiming a Zero shot-down, but in fact only four Zeroes suffered some damage, and all 13 safely returned to base in Wuhan. As the already desperate situation was now irrefutable with the scourge of the new Zero fighters, the Chinese Air Force high-command issued an all-points bulletin to avoid combat engagement against the new air-superiority fighters; however, Chinese fighters would continue with fatalistic courage to face the Zero on numerous occasions, including another large-scale dogfight over Chengdu on 14 March 1941 that saw the Japanese Zero fighters employ new tactics to avoid near-deadly mistakes from the 13 September 1940 air battle experience; the intense dogfight over Chengdu was another devastatingly dark