(Imām Bukhārī narrates): Abū 'Āsim narrated to us, from Imām Mālik, from Sumayy, from Abī Sālih, from Abū Hurairah, may Allāh be pleased with him, he narrates that the Prophet ﷺ said:
The martyrs are (these): the one who drowns, the one who dies of the plague, the one who dies of a stomach disease, the one who dies crushed (under a collapsed structure).
Reference: Sahih Al Bukhari 720