KRAMATORSK, Ukraine — A member of the Ukrainian National Guard opened fire at an aerospace and rocket factory on Thursday, killing five people, the authorities said, and raising anxiety in a region already on tenterhooks as tensions with Russia grow.
Little was known about the soldier behind the attack or his motive, but given the nature of the tightly guarded factory and warnings in recent days that Moscow might stage an act of sabotage as a pretext for invading Ukraine, the shooting drew immediate attention.
The attack took place in Dnipro, one of the largest cities in the country, more than 100 miles from the front line of the war in eastern Ukraine, where the military has been fighting Russian-backed separatists since 2014.
The gunman fled the scene, leading to a sprawling manhunt that lasted for hours before a suspect was taken into custody, according to the police. The man was identified as Artemiy Ryabchuk, and the authorities said he was born in 2001 but released few other details.
The investigation was taking place against the backdrop of a geopolitical struggle.
The Kremlin has been pushing to reduce the Western presence in a region it considers within its sphere of influence, repositioning troops to increase pressure and demanding assurances that NATO will not allow Ukraine to become a member. Earlier this month, the United States said Russia had dispatched intelligence agents and saboteurs into eastern Ukraine to stage a provocation, with industrial infrastructure seen as a potential target.
That made the site of Thursday’s attack of special interest.
The shooting took place at what was once one of the Soviet Union’s largest missile factories. American officials have long seen the factory, commonly known as Yuzhmash, as posing a risk of weapons proliferation.
The Ukrainian police said that the gunman opened fire shortly before 4 a.m., as soldiers were collecting their weapons in a guard house. There were 22 people in the room at the time, the authorities said.
Four of those killed were soldiers, and the fifth was an employee of the factory, the police said. Five other people were wounded.
A statement from Ukraine’s Interior Ministry said that the soldier had turned his weapon on fellow service members who were guarding the plant, and then fled. It said he had fired “for undetermined reasons.”
Later, Denys Monastyrsky, Ukraine’s interior minister, wrote in a post on Facebook that the police were examining the suspect’s medical records since the time of his enlistment, suggesting that the investigation would include the possibility of a psychological disorder.
The attack came only hours after the United States and NATO provided written responses to Russian demands concerning Western nations’ presence in former Soviet states. The initial response from Moscow was chilly.
The rocket factory where the shooting took place has long been a source of concern for Western officials worried about the proliferation of missile technology. After the Cold War ended, it was one of the first locations where the United States directed its attention.
In December 1993, after years of negotiations, Ukraine agreed to give up its nuclear weapons. A few months later, teams of Western scientists were dispatched to the facility to work with the people there to destroy the nuclear weapons that had once been pointed at the United States.
But concerns remained.
Its technical libraries and aging cadre of poorly paid rocket scientists led to worries that designs for rocket engines developed in the Soviet period could be passed along to rogue states like North Korea.
For Russia, the factory’s separation during the Soviet breakup from what had been an integrated space and military industry was seen as emblematic of the economic and scientific disruptions caused by Ukraine’s emergence as an independent country.
The company that now operates the factory makes civilian rockets for satellite launches and has cooperated with NASA on designs for resupply missions to the International Space Station. Its rocket models include the Antares, the Cyclone and the Zenit, but it has struggled to remain profitable.