Beirut is searching for survivors after a massive explosion rocked the Lebanese capital. At least 135 people are dead and 5,000 are wounded.

• Rescuers are searching for survivors after a massive explosion shook the Lebanese capital city of Beirut on Tuesday, leveling buildings and causing extensive damage.
• At least 135 people were reported dead with more than 5,000 others wounded, according to Lebanon's health minister.
• Lebanon's prime minister blamed the ignition of more than 2,750 metric tons of ammonium nitrate improperly stored in the area. An investigation is ongoing.

At least 100 people are dead and 4,000 are injured after a massive explosion on Tuesday shook the capital city of Beirut — with Lebanon continuing its search for survivors on Wednesday.

Lebanese Prime Minister Hassan Diab said the blast was caused by the ignition of more than 2,750 metric tons of ammonium nitrate stored insecurely at a warehouse. The explosion is under investigation.

"I will not rest until we find the person responsible for what happened," Diab told reporters, NBC News said.

Footage of the explosion from several vantage points around the city spread quickly on social media.

The explosion killed at least 135 people and wounded 5,000 others, Lebanon's health minister said, citing a report from The New York Times. Rescuers on Wednesday were searching for survivors amid rubble and leveled buildings.

Some of the city's hospitals were so heavily damaged by the blast they said they couldn't admit all the injured.

Lebanese authorities told CNN's Ben Wedeman that the ammonium nitrate was most likely seized from a ship six or seven years ago.

Local reports said the blast was felt dozens of miles away.

While initial state-media reports said the explosion was caused by a fire at a fireworks-storage facility, Maj. Gen. Abbas Ibrahim, the director-general of Lebanese intelligence, attributed the deadly blast to the ignition of confiscated highly explosive material stored at the local port.

The Lebanese prime minister later named the substance as ammonium nitrate.

President Donald Trump told reporters Tuesday that it "seems like" the devastating explosion was an "attack," citing purported conversations with US military officials.

Three Defense Department officials told CNN there was no evidence suggesting that.

The full extent of the damage remains unclear, but local reports and imagery coming out of Beirut indicate widespread damage in the city.

On Wednesday the country was to hold a national day of mourning.

Beirut Gov. Marwan Abboud said 250,000 people had been left homeless.

The blast rocked the city as Lebanon was dealing with a financial and political crisis, high unemployment and poverty rates, and the coronavirus pandemic.

Other countries offered medical staff and aid, field hospitals, and other aid money.