Yemen's Iran-backed Houthi rebels said they fired a drone that caused an explosion in Tel Aviv early Friday that left one person dead, injured four and set off a new shock for Israel more than nine months into its war in Gaza.

The Israeli military said an initial investigation showed the blast was caused by "the falling of an aerial target" that did not set off alarms. It said air patrols had been stepped up.

The Houthis, who have carried out dozens of attacks against Red Sea shipping to show support for Palestinians during the Gaza war, said their "UAV force" attacked "one of the important targets in the occupied Jaffa region, what is now called Israeli Tel Aviv."

The rebels last Saturday had said they would "not hesitate to expand its military operations... until the aggression stops".

If an attack is confirmed, it would be the first to cause casualties in Tel Aviv since a rocket strike launched from Gaza wounded one person on 26 May. Hundreds of rockets were fired at Tel Aviv in the 7 October attacks that set off the war, but most were intercepted. 

Israeli police said they received hundreds of reports around 3:00 a.m. (0000 GMT) of "a strong explosion".

The blast hit a building in a street near an annex of the US embassy in Israel, according to an AFP journalist, who saw broken windows.

During the search, a man in his fifties was "found dead in his apartment" bearing injuries caused by shrapnel, police said.

The Magen David Adom emergency medical service said in a statement that it treated a man and a woman injured in their home, and two others hurt in the street. All four were taken to hospital with "relatively minor" injuries, it said.

"It may have been an aerial explosion... We were very lucky," said Peretz Amar, the Tel Aviv police commander, adding that "the investigation is ongoing".

'Everything shook'

A Tel Aviv resident told AFP that he was awakened by the explosion and "everything shook".

Police called on residents to "respect safety instructions and not to approach or touch debris or shrapnel that may contain explosives".

The fire brigade said it was possible that a drone had caused the explosion.

The war in Gaza began with the 7 October attack by Palestinian Hamas militants on Israel which resulted in the deaths of 1,195 people, mostly civilians, according to an AFP tally based on Israeli figures.

The militants also seized 251 hostages, 116 of whom are still in Gaza, including 42 the Israeli military says are dead.

Israel's military retaliation has killed at least 38,848 people, also mostly civilians, according to figures from the Gaza health ministry.