You can translate this in an active form. Alternate translation: "the disciples had locked the doors where they were" (See: [[rc://en/ta/man/translate/figs-activepassive]])
Here "Jews" is a synecdoche for the Jewish leaders who might arrest the disciples. Alternate translation: "because they were afraid that the Jewish leaders might arrest them" (See: [[rc://en/ta/man/translate/figs-explicit]])