After you enter the Houston Zoo, you'd have to get through three locked doors -- two of them made of heavy reinforced steel – in order to get to the Malayan tigers.

More importantly, those doors and heavy steel cages are there to keep the tigers from getting to you.

Only today, the tigers Jamu and Pandu preferred to stay outside and to sleep in the shade.

Houston Zoo curator Hollie Colahan reflected on the deadly incident in San Francisco, where one person was killed after a tiger got loose.

“Oh, definitely that's our worst nightmare, to have something like that happen,” said Colahan.

She said the Houston Zoo's Lexan barriers, sheer unclimbable rock walls and a secondary electrical system are installed to keep Houston Zoo visitors safe.

“It's a sheer wall they can't climb it but it discourages them from even trying,” said Colahan.

A decade before these two tigers were even born, a Siberian tiger killed a Houston Zoo keeper.

It attacked him through an observation door that opened to the exhibit. His widow settled a multi-million dollar lawsuit against the designer and builder of the tiger exhibit.

As a result, changes were made at the zoo, which hasn’t had any such incidents since 1988.

"The fences are tall and there is a lake. I feel safe,” said zoo visitor Juan Jose.

However, if a dangerous animal were to escape from the Houston Zoo, they'd issue what they call a Code 99 on the radio. 

Trained zoo employees would go to one of three weapons holding areas.

They are trained to tranquilize if they can and trained to kill if they have to.

Something they hope is never necessary.