Bus bombings returned to the streets of Jerusalem on Monday afternoon when a No. 12 passenger bus exploded and was engulfed in flames near the Talpiot industrial area.

So fierce was the fire that a second nearby bus and a passing car also caught on fire.

In all, 21 people were wounded, at least two of them seriously.

Authorities initially reported that the fire could have been caused by a technical malfunction on the first bus. But police later found evidence that a small explosive device had been placed near the rear of the bus.

Security forces on Monday evening were still hunting at least one suspect and urged the public to be vigilant.

Prime Minister Benjamin Netanyahu vowed that those responsible for the attack would be brought to justice.

At press time, no terror organizations had claimed credit for the blast.