Eight Buddhist monks were killed and more than 20 others injured after being hit ​by a pickup truck driven by an ‌11-year-old boy while on a pilgrimage in Thailand's northeastern province of Mukdahan, officials said on Thursday.

The victims were part of a ​group of 34 Buddhist monks and five ​lay followers undertaking a pilgrimage from a temple ⁠in Mukdahan province to another in neighbouring ​Ubon Ratchathani province, Mukdahan Governor Vorayan Bunarat said at ​a press conference.

Five monks died at the scene, while three others later succumbed to their injuries in hospital, the governor ​said. Another 22 monks and one layperson ​were injured in the crash, including four who are now in critical ‌condition.

"The ⁠driver, an 11-year-old boy with special needs, took the pickup truck from his family home and drove about 10 km (6 miles) before hitting the ​group of monks," ​said Major ⁠General Pairoj Thaiphutra, the Mukdahan provincial police chief.

Police have not filed any ​charges as investigators are still trying to ​establish ⁠the circumstances surrounding the crash, Pairoj said.

Officers have not yet been able to question the boy because ⁠he ​remains in a state of ​shock and is unable to provide a statement, he added.