The second day of the Chicago International Charter School teachers’ strike got off to a chippy start Wednesday morning, with union leaders accusing management of calling in Chicago police officers to “bust up” one of their picket lines — a claim the charter network denied.

Chicago Teachers Union officials said CICS network leaders phoned in about their legal picket line outside Wrightwood Elementary on the Southwest Side, and brought CICS administrators from their downtown headquarters to “intimidate” parents and strikers.

“They intimidated our parents by telling them students would be marked absent and that it would be almost like a black mark against them,” Wrightwood English teacher Dorothy Underwood said. “They bullied us in the picket line.”

Police officials said officers were called about 7:35 a.m. regarding a disturbance blocking the school’s parking lot entrance. The officers spoke with protesters and school administrators, and the entrance was cleared without incident, according to police.

A spokeswoman for Civitas Education Partners, the firm that manages the charter network, said it was a nearby resident who called police to complain about the noise of the protesters’ megaphone.

Striking CTU members then brought their picket line to the River North office of CICS co-founder Craig Henderson on Wednesday afternoon.

“We”re on strike to make sure funds go to our classrooms, not the three different layers of board rooms this company uses to run its schools,” CTU President Jesse Sharkey said.

CTU leaders accuse the management firm of sitting on $36 million in reserve funds — and investing some of it with Henderson’s firm — as it is siphoned off in a complex corporate structure that includes three subsidiary charter management organizations. Civitas says they have $18 million in emergency funds set aside.

Henderson called the union’s claims of a conflict of interest “appalling and disappointing.

“I did manage money in CICS after they developed some reserve funds. I never charged them a fee for them ever,” said Henderson, who retired from the network’s board about three years ago.

“I gave 21 years of my heart and soul to the organization. I probably saved the charter network about $400,000 in management fees. And that money went to the kids.”

The 175 teachers and paraprofessionals went on strike Tuesday at Wrightwood in addition to three CICS high schools across the city: Northtown Academy in Pulaski Park, Ralph Ellison in Gresham and ChicagoQuest in Old Town.

The four affected schools are staying open with reduced staffing during the strike, which is Chicago’s second charter teacher strike this school year and the third ever in U.S. history.

About 270 students showed up for classes Wednesday out of the roughly 2,200 impacted by the strike. That number was up from about 120 kids who arrived to school Tuesday.

The unionized educators’ previous contract expired in August. They want: raises to bring salaries in line with Chicago Public Schools teachers; smaller classes; and more social workers and counselors.

Civitas said teachers rejected a proposal Tuesday night calling for raises totaling 31 percent over a four-year contract. The union disputed that figure, saying offers of raises have come with the caveat of cutting other positions, which Civitas denies.

Both sides were scheduled to return to the bargaining table late Wednesday afternoon.