Santiago, Oct 26 (IANS): As many as 23 of the 35 students injured in an explosion inside a school in the Chilean capital, Santiago on Wednesday are still hospitalised, said the Ministry of Health on Saturday.

The ministry said in a news bulletin that two of the injured remain in a state of "extreme gravity" and eight are in "critical condition," Xinhua news agency reported.

The ministry said there were no deaths in connection with the detonation.

Nicolas Cataldo, the minister of education, told the local press that 12 students were discharged on Friday.

Cataldo ruled out that the incident was an "isolated event," as head of the school Maria Alejandra Benavides previously told the press.

According to local police, a group of students from the Barros Arana National Boarding School, located in the historic centre of Santiago, were making preparations on Wednesday to launch explosive devices on public roads. However, the explosion of the devices occurred in a bathroom under unknown circumstances.