Story highlights Suspects, ages 11 to 18, were "school leavers and dropouts," police chief said

DNA tests may be needed to identify badly burned victims, another police official said

Kuala Lumpur, Malaysia (CNN) Seven suspects -- all of them younger than 19 -- have been arrested in connection with a fire at a school in Malaysia's capital that claimed the lives of 21 students and two adults, state-run media outlet Bernama reported Saturday.

The suspects, who range in age from 11 to 18, were "school leavers and dropouts," Kuala Lumpur Police Chief Datuk Amar Singh Ishar Singh said Saturday during a news conference. They were arrested by Royal Malaysian Police, Bernama reported.

The investigation into the fire's cause continues, Singh said.

Witnesses reported being awoken Thursday by cries for help from inside the burning building, where children appeared trapped by metal window grills.

"I saw children kicking on the grill, but they couldn't get out. My friends and I rushed over and tried to reach them, but we couldn't get in," Shahirman Shahril told CNN.

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