India, Aug. 7 -- The student who carried out the deadly school shooting in Thailand on Friday first shot and killed his grandparents at their home before opening fire at Debsirin Nonthaburi School near Bangkok, police said, revealing new details about the attack that left at least seven people dead.

Among those dead were three teachers, three students and the gunman, who cops said killed himself.

Thai police said the gunman fatally shot his grandparents at their residence before heading to the school in Nonthaburi province, northwest of Bangkok, where he opened fire on students and teachers.

Authorities are continuing to investigate the motive behind both attacks. Police believe the firearm used in the shooting was taken from a member ...