A mother bear with a cub is at large in the area between the Rocca al Mare open air museum (Vabaõhumuuseum) and the shopping mall of the same name, in the Haabersti district of western Tallinn.
The bears were first spotted near the Saku Suurhall indoor arena, leading to the temporary closure of nearby health tracks, only reopened earlier this week, in response.
Police and Border Guard Board (PPA), Rescue Board (Päästeamet) and other personnel are on-site.
The Rescue Board says Vana-Rannamõisa, Saviliiva and Lõuka streets are affected, as well as the museum itself.
Those involved in the search, which includes the use of drones, intend to escort the animals out of the urban area, rather than capture them, ERR's online news in Estonian reports.
The board advises the public to stay away from the area and not to approach the bear and cub under any circumstances, but rather seek shelter in a vehicle or building if spotted.
Still in same district on Thursday afternoon
At a little after 3.15 p.m., the Rescue Board announced that the mother bear had been spotted in forest in the same area as before, meaning local residents and the public should stay indoors for the rest of today and overnight.
"We definitely ask people in the Haabersti area to stay indoors tonight, and not head for the health tracks or go out exploring the streets," the Rescue Board added.
"Bears have been spotted on health trails near Saku Suurhall in Tallinn, which is why some areas are closed for movement," the PPA reported on its twitter page earlier on Thursday morning
"Police, rescue workers and hunters are on-site. If you spot any bears, be sure to report it to 112," the post went on.
Open air sports facilities reopened at the start of the week as national and local government starts lifting its coronavirus emergency situation restrictions. Whether their closure, which was announced by Tallinn City Government on March 24, led to an increasing encroachment of wildlife as has been reported in the international media in other under-restriction locations worldwide, was not reported.
Expert: Unusual for bears to make their way into the city
Marko Kübarsepp, chief specialist of the Environmental Agency's wildlife department, told ERR Thursday afternoon that the bears could have made their way through green areas extending well into the city, adding that they probably inhabit an area not far from city limits in any case.
"There are some beautiful green woods on the edge of the city, which are connected by large ridges. The bears could have come from the area of Keila, or Padise, for example," said Kübarsepp, who thought it likely they would return to their home patch in the evening, if given a chance.
"The bears are definitely disoriented; the city presents a dead end, with densely populated sections. They can't go far beyond that before they will turn around."
Kübarsepp noted it was unusual for bears, and other predatory wildlife such as lynxes and wolves, to enter urban areas, though elk and wild goats have done so more in the past.
The brown bear is native to Estonia, with cases of the animal finding its way into areas of human settlement quite a common occurrence even before the pandemic. Total numbers in Estonia are reportedly in the hundreds.
Editor: Andrew Whyte