In June, a man posing as a reporter for the French newspaper Le Monde had approached Ms. Okuyeva and Mr. Osmayev, saying he wanted to write a profile of them, Ms. Okuyeva had said.
He tried to shoot them, but he was foiled when Ms. Okuyeva, who was armed with a pistol, shot and wounded him, saving herself and her husband, the police said.
On Monday evening, an attacker sprayed the couple’s car with bullets at a railway crossing in the countryside outside Kiev, Anton Gerashenko, a lawmaker, wrote on Facebook. “The heart of a patriot of Ukraine has just stopped,” he wrote.
Mr. Gerashenko wrote that the gunman fired from bushes on the roadside. The police said they were searching the area on Monday evening, but reported no arrests.
In an interview from a hospital bed posted on YouTube, Mr. Osmayev described the attack and said his wife had been killed quickly.
“I was driving,” he said. “When the shooting started, everything was flying about around me. It was an attack on both of us. Amina was hit in the head. I tried to keep driving, as much as I could, but the engine was hit.”
On Wednesday, a bomb hidden in a motorcycle parked on a Kiev street exploded, wounding a member of Parliament, Ihor Mosiychuk, and killing his bodyguard and a bystander.
In March, a gunman shot and killed a former member of the Russian Parliament who had defected to Ukraine. The gunman was shot and killed by the former lawmaker’s bodyguard.
In September, a car bomb in Kiev killed another ethnic Chechen who had fought on the Ukrainian side. Another car bomb killed the journalist Pavel Sheremet in July 2016, and two other bombs killed Ukrainian security service officials this year, in June and March.