Arrest in Islamic school knife incident

A 21-year-old man has been arrested and charged after allegedly walking into an Islamic school armed with a knife in Sydney's southwest.

The man allegedly entered Al-Faisal College in Minto just after 2pm on Thursday, asked if it was a "Muslim school" and spoke to a female teacher before leaving.

Primary school students hid under their desks while high schoolers were gathered in a prayer hall as the school went into lockdown on Thursday afternoon, one mother told AAP.

No one was injured during the incident.

In a statement early on Saturday police said that at about 8.30pm on Friday a 21-year-old man attended Campbelltown Police Station, where he was arrested.

He has been charged with armed with intent to commit indictable offence and was refused bail to appear at Parramatta Local Court on Saturday.