*** Warning – Graphic images ***

At least 13 people, including children, were killed in a bombing outside the Hamid Karzai International Airport in Afghanistan on Thursday morning, Reuters reported, citing a Taliban official.

Pentagon press secretary John Kirby confirmed that an explosion at the Abbey Gate caused a number of U.S. and civilian casualties. He also confirmed a second explosion near the Baron hotel, though he gave less information on the second attack. Two U.S. officials said at least one of the explosions appeared to be from a suicide bombing, Reuters reported.

Fox News reported shortly after the news broke of the explosion that at least three American military members were reportedly were injured in the attack. The bombing also reportedly prompted rapid gunfire exchanges which may be ongoing at press time. A U.S. official told Reuters that U.S. casualty numbers are expected to increase.

Medical and hospital staff bring an injured man on a stretcher for treatment after two blasts, which killed at least five and wounded a dozen, outside the airport in Kabul on August 26, 2021. (Wakil Kohsar/AFP via Getty Images)

The Taliban official told Reuters several Taliban guards were injured in the blast as well. According to local news reports citing Taliban officials, at least 52 people were injured in the two explosions.

Journalists from the region have begun sharing images allegedly of the immediate aftermath of the explosion. Local reports indicate the explosion occurred in a densely populated part of the airport.

Wounded women arrive at a hospital for treatment after two blasts, which killed at least five and wounded a dozen, outside the airport in Kabul on August 26, 2021. (Photo by Wakil Kohsar/AFP via Getty Images)

The U.S. Embassy in Kabul told citizens in an alert on Wednesday to “avoid traveling to the airport and said those already at the gates should leave immediately, citing unspecified “security threats,”‘ according to Reuters.

British Armed Forces Minister James Heappey also told BBC radio intelligence about a possible suicide bomb attack by IS militants had become “much firmer.”

Volunteers and medical staff bring an injured man on a stretcher to a hospital for treatment after two powerful explosions, which killed at least six people, outside the airport in Kabul on August 26, 2021. (Wakil Kohsar/AFP via Getty Images)

Despite warnings, thousands of people have been gathering outside the airport in the hopes of escaping Afghanistan before August 31, when U.S. troops are expected to fully withdraw.

“Western troops are racing to evacuate foreigners and Afghans who helped Western countries during the 20-year war against the Taliban, and to get out themselves by an Aug. 31 deadline,” Reuters reported.

There are more than 5,000 U.S. troops at the airport conducting a “non-combatant evacuation operation,” launched after the Taliban took over the capital on August 14. There are at least approximately 1,500 Americans believed to be still in Afghanistan, according to Secretary of State Antony Blinken.

Kristina Wong contributed to this report.