Russian military officials said the bomb was hidden inside a car on the side of a road and went off as a column of military vehicles drove by on Thursday afternoon.
Two soldiers were also wounded in the attack.
Meanwhile, military officials have said a deadly battle between Russian troops and resistance fighters near the southeastern town of Avtury has subsided.
"Right now the action has practically entered its final stage," Colonel Ilya Shabalkin said.
Vladimir Putin has waged a brutal
war against the Chechen people
At least 25 people, including Chechens, Russian troops and a politician, were killed over two days after soldiers began an operation to hunt down resistance fighters in the town.
Chechen fighters have stepped up anti-Russian attacks before presidential elections which are due to take place on 5 October.
The poll will follow a March referendum which was shunned by international observers. The poll had a Soviet-style turnout of 89.5 percent, and approved Chechnya's place within the Russian Federation.
Plea for dialogue
A group of prominent Russian and Chechen activists and
cultural figures Friday called on Russian President Vladimir Putin to launch peace talks with Chechen rebel president Aslan Maskhadov.
In an open letter to Putin, 33 rights activists, writers, historians and scientists questioned the upcoming polls.
"Why do you think that the presidential elections you announced for October, which will be held in the same conditions as the referendum, will bring stability and an end to the war?" the letter asked.
Russia "refuses to accept respected international mediators in resolving the decade-long military conflict in Chechnya"
It also asked the Kremlin why it "denies all possibility of talks with the Chechen separatists, starting with Aslan Maskhadov who has never adhered to fundamentalist tendencies, a lay politician far more moderate than Yasser Arafat."
The open letter also wonders why Putin "praises George W. Bush, Jacques Chirac or Bill Clinton for their mediation" of the Middle East crisis, yet "refuses to accept respected international mediators in resolving the decade-long military conflict in Chechnya."
Russian troops swept into Chechnya in October 1999, after the first war, which began in 1994, ended in a peace accord in 1996.
After Russian troops withdrew in 1996, Maskhadov was elected president in a poll monitored by the Organisation for Security and Cooperation in Europe. However, since 1999 Moscow has denied his legitimacy saying he has ties with terrorists.
The open letter also states that warfare in Chechnya has killed "at the very least" 18,000 Russian troops, 8,000 rebel guerrilla fighters and 70,000 civilians since 1994.
The March referendum on the republic's future did not "halt either Russian troops or Chechen rebels," who continue their all-out war, complete with heavy artillery and air raids, the letter added.
The letter was signed by human rights activists including Lyudmila Alexeyeva, Sergei Kovalev, Elena Bonner and Lev Ponomaryov, writers like Andrei Bitov, lawmakers including Yuli Rybakov, analysts like Andrei Piontkovsky, and Orthodox priest Yakov Krotov.