One other employee was wounded, RIA Novosti reported.
Suspect Dmitry Vinogradov, 30, who worked at the company, was arrested by police.
Investigators said Vinogradov told them he went on a five-day drinking binge after a pharmacist at the Rigla pharmaceutical company rejected him. When he returned to work Wednesday, he began shooting with a gun in each hand.
The pharmacist is in serious condition. Another co-worker, a man, was said to be in grave condition with multiple gunshot wounds.
The attacker was subdued by company guards, ITAR-Tass reported.
Vinogradov posted a self-pitying statement on a social networking site earlier in the day, investigators said. In it, he said: "everything I've seen and learnt in my life, developed in me the hate to a human being as a species."
He added: "I can only see one way to justify it: by destroying as many fragments of the human compost as possible."