9-1-1 Faces a Deadly New Threat in Tense Preview Clip

The 9-1-1 team is going viral, but not online.

On Thursday's episode of the ABC first responder drama, station 118 firefighters Bobby (Peter Krause), Hen (Aisha Hinds), and Chimney (Kenneth Choi), Buck (Oliver Stark), and Ravi (Anirudh Pisharody) will answer a fire call at a biomedical research laboratory — and Entertainment Weekly has an exclusive look at their arrival in the clip below.

Dispatcher Maddie (Jennifer Love Hewitt) informs the firefighters that the facility's virology unit runs "tier 4 precautions" — meaning they handle the most deadly of "lethal and exotic viruses."

The 118 uses duct tape to seal their suits to their gloves and boots and carry gas masks to protect them as they head into the building, which contains, in Hen's words, "the worst ways to die," including West Nile and SARS.

But the floor on fire (deep below the street level) houses CCHF, or Crimean-Congo hemorrhagic fever, which is described by the World Health Organization as a virus that causes severe viral hemorrhagic fever outbreaks with a case fatality rate up to 40 percent. It's also described by Hen as "Ebola's nastier cousin."

EW's exclusive clip ends with Bobby taking a badge from the leader of the laboratory and leading his team into the danger.

A preview that aired after last week's episode of 9-1-1 shows that things don't really go well from there: After an explosion, Bobby, Hen, Chimney, and Ravi get stuck in the building and Buck is seen screaming from the roof that "They're trapped inside!"

Hen is also seen unconscious as police sergeant Athena (Angela Bassett) shows up asking what can be done to rescue her husband and friends.

Given that this has been touted as a two-part saga, we doubt things will be resolved by the time the credits roll after tonight's episode.

9-1-1 season 8, episode 14, "Sick Day" airs tonight at 8 p.m. ET on ABC.