It said there was an issue with "the booster from today's launch".
Russian officials said all manned space flight missions would be suspended until investigators figure out what went wrong. He added that Russian Federation will fully share all relevant information with the U.S.
Rescue crews then raced to the scene to retrieve them, including paratroopers parachuting to their landing spot, helicopters and all-terrain vehicles, NASA said. A photograph posted on Twitter by NASA showed Ovchinin and Hague embracing their families after being transported back to the Baikonur site. They will spend the night in Baikonur before being flown to Star City, Russia's space training center outside Moscow.
"NASA Administrator Jim Bridenstine and the NASA team are monitoring the situation carefully", the statement continued. Instead NASA astronaut Nick Hague and cosmonaut Alexey Ovchinin returned to Earth in a ballistic return of their capsule from an altitude of over 30 miles.
Even if the Soyuz spacecraft is cleared for launch before December, Hadfield said, it could end up carrying astronauts from Thursday's launch rather than the next scheduled crew.
Speaking with reporters in Moscow before Thursday's launch, Bridenstine said that Russian-American cooperation in space remained strong, amid an investigation into the cause of the leak.
The crew "report they are in good condition", NASA said.
NASA astronaut Nick Hague, a member of the International Space Station (ISS) expedition 57/58, is helped by specialists as his space suit is tested at the Russian-leased Baikonur cosmodrome in Kazakhstan on October 11, 2018.
The astronauts were to dock at the International Space Station six hours after the launch and join an American, a Russian and a German now aboard the station. As rescue crews arrived, Hague and Ovchinin were reported in "good condition" and found out of the capsule.
The booster rocket failure that forced an emergency landing for two astronauts headed to the International Space Station was the first launch accident for Russia's manned-space program in 35 years.
Russian Federation may indefinitely postpone its next manned Soyuz launch planned for December, state-owned RIA Novosti reported, citing an unidentified person.
It can hold a crew of up to six people and at present has three people aboard, two men - a German and a Russian - as well as one female USA astronaut. The crew bailed out at an altitude of 164,000 feet and landed safely in Kazakhstan.