The officers spent the next several hours conducting a thorough search of Dranchuk's apartment.
Dranchuk's wife, Volha Antsypovich, a journalist with the "Komsomolskaya pravda" newspaper, was at home at the time of the raid. "They didn't tell us what they were looking for. From time to time they made a joke, saying, 'Are you going to hand over the gun or not?' Then they began to confiscate all the documents in the apartment -- various leaflets, old newspapers, some notes by Tsimafey. The search lasted three hours," she said.
The officers eventually left, taking three boxes of documents. Dranchuk, an aide to imprisoned opposition politician Andrey Klimau, was taken to KGB headquarters for interrogation.
Speaking to RFE/RL's Belarus Service, Antsypovich said she had received no word of her husband's fate: "We do not have any information about Tsimafey. Every time we call the KGB, we get the same answer: 'There's no information available, you should have called earlier when, for example, there was someone in the reception room' -- or some other excuse. Or they say that the information will be available tomorrow. Tsimafey's mobile phone is now switched off, but just two hours ago it would ring when we dialed. When they were taking Tsimafey away, I saw that they put his phone in an envelope without turning it off. Maybe they did it on purpose, to keep track of who was calling him."
Hours later, KGB officers made another arrest -- Mikalay Astreyka, a coordinator for a group of independent election monitors observing next month's election.
The security officers again seized documents and computers and brought Astreyka in for questioning. Both Astreyka and Danchuk remain in KGB custody today.
Elsewhere, across the country, KGB officers staged numerous raids targeting opposition supporters. At least six activists and electoral observers were subjected to apartment searches, including Alyaksey Trubkin in the northwestern city of Polatsk.
"At 8:30 in the morning, four citizens introducing themselves as KGB officers came to my apartment, along with two witnesses [to observe the proceedings]. They showed a search warrant and began searching," Trubkin said. "When I asked them what they were accusing me of, they didn't answer. They confiscated brochures, books, the [Belarusian-language weekly] 'Niva' from Bialystok [in Poland], the [Minsk-based daily] 'Narodnaya volya,' business cards, materials from the Belarusian Popular Front and the Belarusian Language Society, and other petty things."
The raids came the same day as Belarusian President Alyaksandr Lukashenka handed a stern edict to the country's security forces to step up their vigilance ahead of the presidential vote next month.
Speaking at a government conference on national security, Lukashenka said opposition forces both inside and outside the country would stop at nothing to disrupt the elections and bring "lies and violence" to the Belarusian people.
"You know what pressure has been exerted on Belarus -- from open blackmail to attempts by the West to interfere in internal affairs, and from small provocations to threats of extremism on the part of the opposition," Lukashenka said. "Realizing the lack of chances for a legal win, opponents of the authorities are sweating their guts out to fuel tensions in the country, loosen the foundations of the state and society, and blacken our spiritual values."
The Belarusian leader went on to urge the country's security forces to take "preemptive" measures to ensure national safety during the election season.
The mandate appears to be just the latest measure aimed at neutralizing the influence of Belarus's opposition movement ahead of the 19 March vote.
Lukashenka, who is seeking a third term, has cracked down on nonstate media, scheduled early elections, and amended an already harsh Criminal Code to make virtually any form of political dissent a punishable offense.
Lukashenka's closest rival in the race is united opposition candidate Alyaksandr Milinkevich, who has suggested Belarusians will take to the streets in a so-called "revolution of hope" if they conclude the vote is not free or fair.
(RFE/RL's Belarus Service contributed to this report.)