A Northeast High School teacher was taken to a hospital and "numerous students" fell ill because of the heat on Wednesday, the third day of 90-plus temperatures gripping the region and the first week of the new schedule of pre-Labor Day classes for the School District.

With no immediate relief in the forecast, the district said it would again dismiss students at 1 p.m. Thursday and cancel all after-school activities.

In an email to some fellow staffers at Northeast High School, principal Omar F. Crowder said, "We had a teacher who was taken out of the school by ambulance due to heat-related sickness this morning."

Crowder added that "numerous students" also fell ill due to the heat.

District spokesman Lee Whack said the teacher reported that she was suffering from heat exhaustion and was expected to return to school on Friday.

Whack said 12 students at Northeast, which has an enrollment of nearly 3,400, also reported not feeling well because of the heat.

In a statement, the district conceded that this week has been miserable.

"As heat builds during the day, buildings are experiencing uncomfortable conditions. Because temperatures are remaining high into the evening, many buildings are not cooling overnight," the statement read. "Only 27 percent of the district's school buildings have central air-conditioning."

That did not mitigate the chorus of complaints on the district's Facebook page.

"Why even start classes in August when we all know it's extremely hot in August…bad call School district of Philadelphia you should have left it after the holiday or cancel classes all together …you have them dismissing at 1:00 pm when thats the hottest time of the day," one woman texted.

The decision to start classes on Monday was several years in the making. The now-defunct School Reform Commission voted in late 2016 to make the change, with the thinking that having more instructional days earlier in the year would be better for the students.

District officials said then that they considered the possibility of summer heat, but saw little difference in the average temperatures in late June and early September.

"We want to start with a full week and get into a routine," Superintendent William R. Hite Jr. said earlier this month.

Instead, the district is opening with shortened days under oppressive conditions.

As for the future of the pre-Labor Day schedule, Whack said: "We don't want to make a knee-jerk assessment."

In a Wednesday letter to Hite, State Rep. Rosita C. Youngblood (D., Phila.) said she had become "increasingly worried about the students" in the district and their instructional time during the heat wave.

Youngblood asked Hite to list how many district buildings have air-cooling systems, noting that Hite had said in a recent television appearance that the number was more than 60 percent, but that a recent news report said the figure, according to the district, was only 40 percent.

Whack said 59 school buildings —  27 percent of the district's total — have central air. Some of the others are cooled with window or wall units, while others only have fans.

In his email, Crowder, who later referred a reporter's questions to the district, said his school had received 50 fans and would request more as needed.

Whack said schools were given 300 fans for summer programs this year and an additional 150 were sent out in the last two weeks.

Two schools recently got upgraded with central air, and other improvement projects are in the pipeline.