Washington, Aug 1 A US federal judge in Seattle has blocked the release of software that allows consumers to 3D-print firearms.
The order came just hours before their scheduled online distribution by a Texas group that had reached an agreement with the Donald Trump administration to do so, Efe news reported.
Gun access advocacy group Defense Distributed was due to put downloadable gun blueprints online on Wednesday.
The settlement with the Trump administration was reached in June that would have allowed it to legally publish the instructions even via online posts.
However, eight states and the District of Columbia sued the government on Monday to block the settlement, arguing that untraceable guns were a safety risk, the BBC reported.
In a sudden tweet on Tuesday, even President Trump said: "I am looking into 3D plastic guns being sold to the public. Already spoke to NRA, doesn't seem to make much sense!"
He was referring to the National Rifle Association, the powerful US pro-gun organisation and lobbying group.
Almost simultaneously, came US District Judge Robert Lasnik's temporary restraining order halting the release hours before the August 1 deadline, saying the blueprints could fall into the wrong hands.
The agreement with the Texas-based Defense Distributed was the conclusion of a five-year legal battle in which the former Barack Obama administration argued before two federal judges.
While the Supreme Court refused to hear the case that the downloadable manuals for how to print plastic rifles and pistols violated firearms export laws.
However, the Trump administration had suddenly reached the agreement two months back and given approval for publication of the manuals in any form.
It even said that the US government will pay $40,000 to cover the legal fees incurred by Cody Wilson, the founder-director of Defense Distributed.