Jewish students in Sydney returned to school on Friday with a heightened security presence, days after police said they foiled a planned antisemitic attack in the city using a trailer filled with explosives.

The police said they were investigating whether “overseas actors” were involved in the vandalizing of synagogues and a day care center.

Sydney restaurateur Judith Lewis couldn’t save the mezuzah, a framed parchment inked with Hebrew prayers, that was hanging in her family’s café when arsonists set it alight in the early hours one Sunday in late October.