At least 11 employees were taken to hospitals and residents were urged to shelter in place on Tuesday after an explosion at a Louisville, Kentucky, business.

The Louisville Metro Emergency Services reported on social media a “hazardous materials incident” at 1901 Payne St., in Louisville. The address belongs to a facility operated by Givaudan Sense Colour, a manufacturer of food colorings for soft drinks and other products, according to officials and online records.

Louisville Mayor Craig Greenberg said emergency teams responded to the blast around 3 p.m. News outlets reported that neighbors heard what sounded like an explosion coming from the business. Overhead news video footage showed an industrial building with a large hole in its roof.

“The cause at this point of the explosion is unknown,” Greenberg said in a news conference. No one died in the explosion, he added.

Greenberg said officials spoke to employees inside the plant. “They have initially conveyed that everything was normal activity when the explosion occurred,” he said.

The Louisville Fire Department said in a post on the social platform X that multiple agencies were responding to a “large-scale incident.”

The Louisville Metro Emergency Services first urged people within a mile of the business to shelter in place, but that order was lifted in the afternoon. An evacuation order for the two surrounding blocks around the site of the explosion was still in place Tuesday afternoon. 

A rare square 37-carat emerald owned by the Aga Khan fetched nearly $9 million at auction in Geneva on Tuesday, making it the world’s most expensive green stone.

Sold by Christie’s, the Cartier diamond and emerald brooch, which can also be worn as a pendant, dethrones a piece of jewelry made by the fashion house Bulgari, which Richard Burton gave as a wedding gift to fellow actor Elizabeth Taylor, as the most precious emerald.

In 1960, Prince Sadruddin Aga Khan commissioned Cartier to set the emerald in a brooch with 20 marquise-cut diamonds for British socialite Nina Dyer, to whom he was briefly married.

Dyer then auctioned off the emerald to raise money for animals in 1969.

By chance that was Christie’s very first such sale in Switzerland on the shores of Lake Geneva, with the emerald finding its way back to the 110th edition this year.

It was bought by jeweler Van Cleef & Arpels before passing a few years later into the hands of Harry Winston, nicknamed the “King of Diamonds.”

“Emeralds are hot right now, and this one ticks all the boxes,” said Christie’s EMEA Head of Jewellery Max Fawcett. “…We might see an emerald of this quality come up for sale once every five or six years.”

Also set with diamonds, the previous record-holder fetched $6.5 million at an auction of part of Hollywood legend Elizabeth Taylor’s renowned jewelry collection in New York.