More than 20 visitors at a popular temple in Kyoto complained of throat and other pains Wednesday morning following a strange chemical smell, with four of them hospitalized, local authorities said.

None sustained life-threatening injuries in the incident at Nanzenji temple. It is not yet known what caused the smell, the temple said.

The pungent odor is believed to have emanated from around a toilet located near the Zen temple's main building, which is designated as a national treasure. Around 70 people evacuated the temple.

Visitors received emergency medical treatment on the premises of the temple after around a dozen ambulances and fire engines were dispatched to the site.

An official of the temple called firefighters around 11:30 a.m. after one of the visitors reported a "strange smell."

"Some people around me suddenly started coughing or even shedding tears. I immediately ran away from the site," said Yoshie Iwata, a 42-year-old visitor from the city of Sakai, Osaka Prefecture.

The temple closed its doors to visitors following the incident but will reopen from Thursday, it said.

The temple opened in 1291 and is the head temple of the Nanzenji school of Rinzai Zen Buddhism.