Semba is a mom.

The 24-year-old African elephant at Reid Park Zoo delivered the female calf at 10:55 p.m. Wednesday.

Both Semba and the calf are doing well, zoo officials said Thursday.

It's Semba's third birth, but it's the first elephant born at the zoo, said officials who noted the calf was born on Tucson's 239th birthday.

Mom and baby are spending quiet time in the Click Family Elephant Care Center, Vivian VanPeenen , the zoo's education curator said in a news release.

Semba and her 245-pound calf will not be available for viewing for some time.

Go online to see the Semba blog and the latest photos.

A crew of keepers and volunteers have been keeping a close eye on Semba around-the-clock since July.

About 10:35 p.m Semba began to exhibit signs of active labor, including laying down, walking backwards, and extending her tail.

She progressed quickly and delivered without staff intervention, VanPeenen said.

The calf hit the ground at exactly 10:55 p.m., took her first breath immediately and stood up within minutes.

She was nursing within the hour.

"We are beyond excited," Fred Gray, Director of Parks and Recreation, said in the news release. "I could not be more proud of our staff for their hard work and preparation for this important day. Our top priority is the health of Semba and her calf — and I’m pleased to hear they are both doing well."