D.C. Fire and EMS medics responded to a fresh spike in patients showing symptoms of a synthetic marijuana overdose as medics took dozens of people to hospitals in a 24-hour period Wednesday through Thursday.

Cases appeared to be tapering citywide to a few a day in the past several weeks, after a previous overdose surge in July that included three deaths after the use of K2 or synthetic cannabinoids.

The new spate included suspected overdoses in the vicinity of North Capitol and O streets NW, where children walking to school passed at least one victim, according to a letter to parents from the school.

On Wednesday night, medics responded to 27 patients and took 20 of those to hospitals . By early evening Thursday, they had evaluated 22 patients and transported 19 of them.

Among the incidents, EMS crews evaluated 16 people who collapsed about 8 a.m. Thursday near North Capitol and O streets NW. The crews took seven from there to hospitals, said Doug Buchanan, a fire department spokesman.

The large-scale incident happened near Mundo Verde Bilingual Public Charter School. D.C. police school resource officers ensured the school grounds were secure and recess was restricted to campus, the school’s letter stated.

“Some students walking with families to school this morning walked past at least one of the adults. There were no incidents on or abutting school property,” the letter said. “We know that some of our students may struggle to understand why these events happen and, more importantly, how they can be prevented. Mundo Verde staff will continue to reassure students, that schools are generally very safe places for children, reiterating what safety measures and student supports are in place.”

Also Thursday, medics performed CPR on one man after they were called about 7 a.m. to an area outside the Reeves Municipal Center at 14th and U streets NW, Buchanan, said.

In July, after a sharp increase in suspected K2 overdoses officials launched a public information campaign to discourage people not to use the low-cost drugs.