TROOPS loyal to the Soviet Union's new hard-line government seized key installations in the Latvian capital of Riga on Aug. 19. They killed a minibus driver and wounded one of his passengers, the republic's radio reported.The shooting, the only death reported since the Kremlin takeover, came as the Soviet military staged a show of strength in the three separatist Baltic republics. Troops took control of Latvia's interior ministry and television center, and about 40 military vehicles rolled past the Lithuanian parliament, heavily barricaded since clashes last January which left 13 people dead. Troops set up a camp outside the capital, Vilnius. Troops also seized Lithuania's only remaining television tower, in the city of Kaunas, as well as the television studios there and the international telephone exchange. "We are now broadcasting only from our antenna in parliament," a parliamentary spokeswoman said. Two large columns were also spotted in Estonia, the third of the Baltic republics seeking to reclaim the independence they enjoyed before-World War II. The Estonian news agency ETA said Gen. Fyodor Kuzmin, appointed military commandant in the Baltic district, ordered separatist Estonian President Arnold Ruutel to dissolve all military formations and ban demonstrations. Ruutel had refused. Latvian radio reportedly quoted eyewitnesses as saying the two bus victims were shot by men in assault troopers' uniforms and black berets - a reference to elite troops under the jurisdiction of the Soviet interior ministry. The ministry was not immediately available for comment on the allegation. Leaders in all three Baltic republics denounced the takeover of power in the Soviet Union by the hard-line State of Emergency Committee, but other republics were more cautious. Lithuania's mass Sajudis nationalist movement said it would back a general strike in the republic - as called for by Russian leader Boris Yeltsin - if Mikhail Gorbachev's removal were followed by an attempt to oust the Vilnius government. From his barricaded parliament, nationalist Lithuanian President Vytautas Landsbergis urged peaceful resistance.