Video by Eric Keith

A power outage hit St. Joseph Wednesday morning, spreading north into areas near Maryville, Mo., and south toward Gower. Kansas City Power & Light said the outage that started shortly before 10 a.m. affected about 48,800 customers in Andrew, Buchanan, Clinton and DeKalb counties.

Power for most residents was out for between one hour to 90 minutes.

At the Townsend and Wall Lofts, Sixth and Francis streets, Maribeth Klindt found herself in darkness, screaming for help when she became stranded on the building’s elevator. Eight firefighters hiked to the third floor with axes and other emergency gear and walked through some dark hallways before arriving at the elevator doors. When they were opened, firefighters turned around and headed down a floor. A few minutes later, a universal key opened the elevator doors on the second floor and firefighters helped a badly shaken Ms. Klindt onto solid ground.

“I’d never been stuck in one before,” Ms. Klindt said. She said she had no desire to ever be stuck again.

A number of people were stuck in elevators, but most were able to escape with assistance from others in their building, said Russell Moore, a battalion commander. The department answered two more calls in the next hour to rescue individuals.

KCP&L officials believe the outage was caused by “a very uncommon event” involving routine testing and a dead tree in the North Side. Crews had taken down part of the transmission system Wednesday for required testing, said Matt Dority, utility district manager.

One transmission line in the North Side apparently sagged beyond its normal level to touch a dead tree, triggering the shut down.

“It’s kind of similar to a breaker tripping off at your home,” Mr. Dority said. “We immediately were aware of the situation and began the restoration process.”

Power substations were brought back on in phases to prevent an overload.

Out on the city’s East Side, police directed traffic on the Belt Highway. Hy-Vee remained open when the store’s battery-powered generators kicked in.

Hy-Vee’s foresight paid off. “We decided to take an early lunch,” said Kim Thimes, an employee at Progressive Community Services, who drove to the store with her friend Pam Tyler.

Over at the Ramada Inn, Kevin Sattler, a visitor from North Dakota, said, “I took my morning shower in candle- and cell-phone light.”

Heartland Health was without power for a little less than an hour, said spokeswoman Marcy George. The medical center and clinics were never without back-up power, immediately switching to generators. Heartland also enacted its emergency incident command system. Representatives from each department met to ensure all departments communicated with one another.

KCP&L said it restored power to the last customer’s home at 11:30 a.m.

Ahmad Safi can be reached at ahmadsafi@npgco.com. Marshall White can be reached at marshall@npgco.com. Lifestyles reporter Erin Wisdom contributed to this story. She can be reached at ewisdom@npgco.com.