Seven people, including four children, died on May 22 in northern Thailand, officials said on Tuesday. Strong winds from a rainstorm caused a metal roof on a school’s activity center to collapse on the people who were taking shelter under it.

The latest casualty was a 6-year-old boy who died late Monday night in a hospital after the collapse at the Wat Nern Por primary school, according to the public relations office in Phichit province, 300 kilometers (185 miles) north of Bangkok.

Several students had gone inside the activity center to shelter from the rain when the roof collapsed, according to a Facebook post from the official disaster prevention department, and 18 people were hospitalized.

The meteorological department issued a warning for heavy rain in northern Thailand this week. Monday was also the official start of the rainy season.