Updated

Three diplomatic security agents, as well as a State Department contractor, were among the Americans injured during the terrorist attack last September on the U.S. Consulate in Benghazi, Fox News has learned.

According to a State Department official, who confirmed Fox's reporting on the condition of anonymity, two diplomatic security agents were injured, including one “seriously,” at the CIA facility known as the “annex” and a third suffered smoke inhalation at the consulate where Ambassador Chris Stevens was killed.

Four Americans, including the U.S. ambassador, were killed in the attack, and the Obama administration faced intense criticism from Republicans in the aftermath over security problems and apparent inconsistencies in officials explanation of what happens. Lately, however, the focus has turned to the attack's survivors, who still have not been named.

Separately, a diplomatic security source told Fox News the State Department diplomatic security agent who was in the most serious condition suffered a severe head injury during the second wave of the attack at the annex from mortar and rocket-propelled grenades.

This agent was described as the likely State Department employee visited at Walter Reed Medical Center by Secretary of State John Kerry in January -- a visit first confirmed by Fox News' James Rosen in a recent interview with Kerry.

While not denying the details, the State Department official offered no comment on the nature of the injuries or whether the agent was visited by Kerry or Hillary Clinton before she left office.

On Tuesday, Fox News learned that congressional staffers from the House Armed Services, Foreign Affairs, Intelligence, Judiciary and the Government Oversight committees met for a closed door "status report" on their committees’ respective investigations into the Benghazi terrorist attack.

A congressional source familiar with Tuesday’s meeting told Fox News they believed approximately 37 individuals were in Benghazi on behalf of the State Department and CIA on Sept. 11.

With the deaths of Ambassador Stevens, State Department employee Sean Smith and two former Seals Tyrone Woods and Glen Doherty who worked for the CIA annex, about 33 were evacuated. Of the injured, the congressional source said they believed two were treated at Walter Reed and a third had an "extended stay" for treatment in Germany after the evacuation.

The State Department official offered no comment on these details.

Rep. Frank Wolf, R-Va., has gathered about 60 signatures in support of a select committee to investigate the Benghazi terrorist attack. Wolf has said the committee is the most thorough and efficient approach to resolving the lingering underlying questions rather than the competing and overlapping committee jurisdictions.

Wolf, along with Rep. Dana Rohrabacher, R-Calif., and leading Senate Republicans John McCain of Arizona, Lindsey Graham of South Carolina and Kelly Ayotte of New Hampshire have pressed the State Department for answers and access to the survivors by congressional investigators.

As of late Thursday, congressional requests have apparently gone unanswered.