IRKUTSK — A laboratory technician at a Russian infectious-disease research institute has died in Siberia, triggering the quarantine of dozens of people and international scrutiny.

Darya Shipilova, 28, a technician at the Irkutsk Research Anti-Plague Institute of Siberia in Shelekhov, died after being diagnosed with pneumonia of unknown origin, according to Rospotrebnadzor, Russia's federal agency for consumer protection and epidemiology. The agency said no microorganisms associated with the employee's work duties were detected in samples taken from the patient.

Anna Popova, head of Rospotrebnadzor, traveled to Irkutsk on Friday. Local governor Igor Kobzev confirmed the visit and described it as an extraordinary meeting of the regional anti-epidemic commission to address what officials characterized as a "suspected case of a particularly dangerous infection." Kobzev announced the woman's death on Telegram.

U.S. Secretary of State Marco Rubio called for greater transparency from Russia regarding the incident. "I think it's incumbent upon Russia to obviously share more information with the world," Rubio said on Tuesday. "We're watching it very closely, hour by hour."

President Donald Trump offered U.S. assistance on Monday. "Anybody that has that kind of a problem, we're always willing to help," Trump told reporters before departing the White House for Nebraska.

Maxim Modin, mayor of the Shelekhovsky district, said regional authorities are implementing "a comprehensive set of anti-epidemic measures." The inpatient facility at the hospital where the worker was treated has been placed under quarantine. Several departments within the hospital have stopped discharging or admitting patients. Local media reported that other hospitals in the region have also closed.

Irkutsk authorities canceled the annual community cleanup event scheduled for the weekend. The institute declined to comment when reached by phone.

Residents expressed concern about the situation. "While there are no visible changes in the city, my acquaintances are slightly panicking," said Ekaterina, a local resident.