Assassins on motorcycles killed one Iranian nuclear scientist and wounded another Monday, by putting bombs on the windows of the scientist's cars before speeding away.
During a press conference Monday, Iranian President Mahmoud Ahmadinejad accused Israel and Western governments of being behind the killing.
Ahmadinejad said that "undoubtedly the hand of the Zionist regime and Western governments is involved" in the killing. But he said the assassination won't stop Iran from pursuing its nuclear programs.
Two other scientists in Iran's highly controversial nuclear industry have been killed in recent years. Washington has strongly denied allegations of links to previous attacks.
There are several active armed groups that oppose Iran's ruling clerics, but it's unclear whether they could have carried out the apparently coordinated bombings in the capital.
Iran has blamed Israel, even accusing the Jewish nation of trying to derail Iran's nuclear program.
The Islamic republic also claims other nuclear scientists have been abducted and that someone recently hit Iran's uranium-enrichment centrifuges with a computer virus meant to destroy them.