Britain pledged Thursday to send sophisticated medium-range rocket systems to Ukraine, joining the United States and Germany in equipping the embattled nation with advanced weapons for shooting down aircraft and knocking out artillery.

Western arms have been critical to Ukraine’s success in stymieing Russia’s much larger and better-equipped military during a war now in its 99th day. But as Russian forces closed in on a key city in recent days, the Ukrainian government said its fighters needed better rocket launchers to prevail.

A Kremlin spokesman again warned of “absolutely undesirable and rather unpleasant scenarios” if the latest Western-supplied weapons were fired into Russia.

“This pumping of Ukraine with weapons … will bring more suffering to Ukraine, which is merely a tool in the hands of those countries that supply it with weapons,” Kremlin spokesman Dmitry Peskov told reporters.

A gunman carrying a rifle and a handgun killed four people at a Tulsa medical building on a hospital campus, police said, the latest in a series of deadly mass shootings across the country in recent weeks.

Wednesday’s shooting on the campus of Saint Francis Health System happened the same week that families in Uvalde, Texas, began burying the dead from the deadliest school shooting in nearly a decade.

The victims and gunman in Tulsa were found on the second floor of a medical office where an orthopedic clinic is located, police said. The shooter, whose name has not been released, died from an apparent self-inflicted gunshot wound, Tulsa Police Department Deputy Chief Eric Dalgleish said.

The hospital said in a statement that it was “grieving the loss of four members of our community” but did not immediately identify the dead.