Emails threatening terror attacks led to the evacuation of hundreds of businesses, media outlets and foreign embassies in Ukraine this week.

Ukrainian national police searched dozens of properties targeted by the threat, including the Kyiv office of VOA sister network Radio Free Europe/Radio Liberty, according to reports. Police said the searches did not find evidence of explosives.

The country’s Foreign Ministry said that about 60 of its foreign diplomatic missions also received the threatening emails, leading some of them to suspend services.

The email, which appeared linked to an anti-Ukraine Telegram group, mentioned the names of three journalists with RFE/RL’s Schemes investigative news desk.

The journalists recently reported on how Russian intelligence recruits individuals to carry out arson attacks on vehicles belonging to military personnel or conscription center workers.

RFE/RL President Stephen Capus said the network is working with authorities in their investigations.

“We will not be intimidated and stand behind our reporters who will continue to bring news to Ukrainian audiences without fear or favor,” said Capus in a statement.

At least four other media outlets were targeted, including the Kyiv Independent, Ukrainska Pravda, Liga.net and the public broadcaster Suspilne.

The Kyiv Independent reported that the email it received claimed that explosives had been planted in their office, as well as at the RFE/RL office and the U.S. Embassy in Kyiv.

“I have planted several explosive devices in your building, and very soon it will explode,” the email read.

A police search of the Kyiv Independent found no evidence of explosives, the media outlet reported.

Police have examined more than 2,000 threatening messages, which they said appear to come from a Russian IP address. A criminal case has been opened for “knowingly false reports of threat to the safety of citizens.”

The messages are described as matching “the style of Russian intelligence services,” a police statement said, adding that Russia is “waging a hybrid war against Ukraine, trying to cause mass panic and exhaust the system of state and law enforcement agencies.”

The New York-based Committee to Protect Journalists denounced the intimidation of RFE/RL’s reporters and called for an investigation.

“Ukrainian authorities must ensure the safety of the journalists and hold the perpetrators to account,” said Gulnoza Said, the CPJ Europe and Central Asia Program coordinator. “Journalists must be able to work safely, without fear of retaliation.”

According to RFE/RL Schemes, the group that claimed responsibility for the alleged planting of explosives has been using social media to spread messages that offer money in exchange for damaging Ukrainian military vehicles.

A spokesperson for the Security Service of Ukraine said Russia was trying to make it look like arson attacks are being carried out by Ukrainians instead of being instigated by Moscow.