Detailed Instructions: In this task, given a sentence in the English language, your task is to convert it into the Japanese language.
Q: Small explosions were heard soon after, and CS gas and stun grenades are also believed to have been used.
A:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
その後すぐに小さな爆発音が聞こえ、CSガスと閃光弾も使われたものと考えられている。