3-star US general pushing Saudis to investigate deadly Yemen strike: Pentagon Local officials say dozens of children were killed when their bus was hit.

The three-star American general dispatched by Defense Secretary James Mattis to look into last week's deadly Saudi airstrike in Yemen is pushing Riyadh to conduct a "timely and transparent investigation" into the incident, according to a Pentagon spokesperson.

In a statement on Monday, Lt. Cmdr. Rebecca Rebarich told ABC News that the general "adjusted his already scheduled visit to Saudi Arabia to discuss the incident with the Saudis and look into the situation."

Rebarich later identified the general as Lt. General Michael X. Garrett of U.S. Army Central/Coalition Forces Land Component Command.

The airstrike occurred last Thursday morning, killing at least 50 people including dozens of children traveling on a bus in the country’s Saada Province, local health officials said.

Saudi officials originally contended that the strike was a "legitimate military action."

On Friday, the Saudi-led coalition announced via the Saudi Press Agency that it would investigate the attack. According to the agency, a senior official in the coalition made the decision after having seen media reports, including reports from relief agencies, about the incident.

The area is a stronghold for the Houthis – an Iranian-backed rebel group that overthrew the Yemeni government in 2015. The U.S. has backed a coalition led by Saudi Arabia and the United Arab Emirates to restore the government.

On Sunday, Mattis told reporters traveling with him to Brazil that he had "dispatched a three-star general into Riyadh to look into what happened here and if there is anything we can do to preclude this from the future."

"The general discussed investigative processes and prevention of civilian casualties with the Saudis and the need for a timely and transparent investigation into this incident," Rebarich said. "He pressed the Saudis to devote the resources and oversight required to do a thorough and complete investigation and release the results to the public."

Rebarich stressed that Mattis never said the general would be conducting an investigation, but urging the Saudis "to expeditiously and thoroughly investigate this tragic incident."

Mattis' statement echoed what State Department spokesperson Heather Nauert said last week when she called for the coalition to conduct "a thorough and transparent investigation."

The U.S. backs the Saudi-led coalition by supplying bombs, intelligence, and fuel for Saudi planes.

Still, Rebarich told ABC News last Thursday that "U.S. Central Command was not involved in the airstrike in Saada."

"U.S. military support to our partners mitigates noncombatant casualties, by improving coalition processes and procedures, especially regarding compliance with the law of armed conflict and best practices for reducing the risk of civilian casualties. The final decisions on the conduct of operations in the campaign are made by the members of the Saudi-led coalition, not the United States," she said.

On Sunday, Mattis told reporters that the U.S. is "not engaged in the civil war," emphasizing that the U.S. military does not do any dynamic targeting for the coalition.

"We will help to prevent the killing of innocent people, we're very concerned about the humanitarian situation," Mattis said, adding, "Wars are always tragic, but we've got to find a way to protect innocent in the midst of this one."

Col. Turki al-Malki, a spokesman for the coalition in Yemen, said last week that the coalition had launched an operation in Saada in response to Houthi fighters firing a missile on the Saudi city of Jizan on Wednesday evening.

The International Committee of the Red Cross (ICRC) said its medical teams received the bodies of 29 children, all under the age of 15. They also received 48 injured people, including 30 children, the ICRC said.

Yemen’s rebel-run Al Masirah TV aired footage of injured children weeping as blood streamed down their faces. Some of the children carried blue UNICEF backpacks, spotted with blood.