SANTIAGO, Oct. 25 (Xinhua) -- Twenty-three of the 35 students injured in an explosion inside a school in the Chilean capital on Wednesday are still hospitalized, the Ministry of Health said on Friday.

Of the injured, two remain in a state of "extreme gravity" and eight are in "critical condition," the ministry said in a news bulletin.

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 center 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. ■