The authorities in Tel Aviv said they were responding to reports of an explosion in the central part of the city early Friday morning that injured at least two people.

Zaki Heller, a spokesman for Israel’s national emergency service, also known as Magen David Adom, said in a statement that its hotline had received a report at 3:21 a.m. that an object had exploded in a building. The Tel Aviv District Police said that a large number of forces were responding.

The cause of the blast was not immediately clear, but the Israeli military said in a statement that it was looking into reports that there had been “an aerial target.”

The two injured people were “lightly wounded” by shrapnel and were conscious, the emergency service’s statement said.

Witnesses described a “very loud explosion” that could be heard miles away.

This is a developing story.