The death toll in the explosion that saw a UPS cargo plane lose an engine and burst into flames, has risen to 13, Craig Greenberg, the Louisville mayor, has confirmed as UPS released the names of the three victims on the plane.

“On my way to the Teamsters’ vigil, I learned of a 13th person that died as a result of the UPS flight 2976 plane crash. My heart is with the families, friends and colleagues of all who were lost in this week’s tragedy. We will get through this together,” Greenberg wrote in a social media post.

A statement from UPS listed the pilots aboard the McDonnell Douglas MD-11 as Captain Richard Wartenberg, First Officer Lee Truitt, and International Relief Officer Captain Dana Diamond.

“Our hearts go out to every UPSer who has been impacted and all in our Louisville community – supporting you and ensuring you receive the care and resources you need is our priority,” the company’s statement read.

“Our hope is that we have located all of the victims at this point. But again, we do not know,” Greenberg said earlier in the day.

A federal investigator announced earlier on Wednesday the UPS cargo plane’s left wing caught fire and an engine fell off shortly after takeoff from the Louisville Muhammad Ali international airport, causing the plane to crash and explode into a fireball.

The National Transportation Safety Board has said it is investigating the plane’s maintenance history which was in Texas for repairs weeks before the crash.

Reuters reported flight tracking data showing the plane was on the ground in San Antonio, Texas, from 3 September to 18 October.

“We are aware that this aircraft was there in San Antonio,” said Todd Inman, an NTSB member, on Thursday, without giving a specific time frame. “We will look at every piece of maintenance that was done, even from the San Antonio time, all the way to the date of the flight.”

The cockpit voice recorder and data recorder were recovered, and the engine was discovered on the airfield.

The recorders – known as black boxes – were built to withstand crash impacts and intense heat from fires, and they appeared to be intact when located amid the crash debris. Investigators plan on reviewing data from the black boxes.

Inman said the plane’s final data recordings showed an altitude of 475 ft, and a speed of 210 mph before the crash.

Singapore-based ST Engineering, which said it provides airframe maintenance for UPS’s MD-11 aircraft and operates a repair facility in San Antonio, declined to comment, but said it would cooperate fully when relevant authorities reached out to it.

According to Federal Aviation Administration records dated 18 September, a crack on a structural piece inside the center wing fuel tank required repairs.

Meanwhile, UPS Worldport operations resumed Wednesday night with its Next Day Air, or night sort, operation, spokesperson Jim Mayer said. All three runways at Louisville Muhammad Ali international airport were also open again.

The UPS package handling facility in Louisville is the company’s largest. The hub employs more than 20,000 people in the region, handles 300 flights daily and sorts more than 400,000 packages an hour.

A candlelight vigil was held on the evening of 6 November by local Teamsters Union, which represents workers at the Louisville airport, the company’s largest air cargo hub.

Teamsters Local 89, which represents UPS workers, began the vigil with a moment of silence at 5.14pm, the approximate time of the crash two days earlier.

“This incident was so sudden, so unexpected,” the mayor told the crowd of 200. “No one had a chance to say goodbye to any of those who we have lost.”

Associated Press contributed reporting