Lions in Kenya's Masai Mara reserve were poisoned Saturday night when they ate a poisoned cow carcass, according to Discovery. Eight lions of the Marsh Pride, made famous as the stars of BBC's "Big Cat Diary" series, were poisoned, with two confirmed deaths, one missing and five lions being treated by vets.

"Five more lions are in critical condition. The poisoning of lions in the Mara is a disgrace to all Kenyans and is a very serious offence," said Kenya's Wildlife Direct Charity's Paula Kahumbu.

"I am sick to the heart to hear of the poisoning of the Marsh Pride lions, and horrified to think of the pain they suffered as they died," said Kenyan conservationist Saba Douglas-Hamilton, a television presenter who worked on show.

Zoologist Jonathan Scott, one of the show's original presenters who has followed the Marsh Pride for 40 years, called the poisoning "end of an era."

Bibi, the 17-year-old female lioness, a celebrity thanks to the long-running series, is one of the lions that died. Missing is another favorite, Sienna.

Grazing of livestock, although illegal on the reserve, is common at night when authorities aren't around. The livestock faces nocturnal predators such as lions, angering the herders.

"But in the last few years, the situation has escalated beyond all reason," added Scott, according to National Geographic. Herders in the area have used poison and spears to kill some of the lions.

"Big Cat Diary" ran from 1996 to 2008.

Kenyan Wildlife Services has made three arrests, according to BBC News. If found guilty, the suspects face hefty fines up to the maximum of $196,000 or life imprisonment.