It was very short notice.

Just before Shabbat, President Donald Trump, finishing off his first week in office, signed an executive order banning immigrants from some countries, instituting the so-called “Muslim ban” for which he had called during his campaign, causing havoc and heartache at airports around the world.

On Saturday night, Jewish women, many of whom had just learned about the situation after havdallah, just before 6 o’clock, joined with Muslim and Christian women and started to organize.

On Sunday, at least 300 people gathered in Teaneck to rally against those executive orders. The group that organized it, Teaneck Together, managed to get a police permit, speakers, and an impassioned crowd, using social media, their own friendship networks, and a shared sense of outrage. “We did everything via phone and Facebook on Saturday night,” Shana Dworken, one of the organizers, said.

The Facebook group that was the rally’s seed was created right after Mr. Trump’s inauguration, by women who had listened to the speech, been appalled by its darkness and the implications that darkness evoked, and “decided that we had to do something,” Ms. Dworken said.  “This was a way to do something. We couldn’t go to any of the marches” — particularly because they all were on Shabbat, and so would have required a great deal of planning and often intricate childcare arrangement — “so we started this group. There wasn’t a master plan, just a desire to support one another, and to build bridges. So we started adding people, with the intent that we could mobilize if something came up.

“But we didn’t realize that something would come up so fast. So Yasmeen Al Shabeb, Tovah Gidseg, and I started organizing.”

Ms. Gidseg, like Ms. Dworken, is Jewish; Ms. Al Shabeb is Muslim. One of the good things to have come out of the situation is that communities that had not been comfortable with each other – often for deep-seated and real historical reasons – have come to work together, and to build friendships that span the gaps between them.

The three women weren’t faced with that sort of ideological question on Saturday night, though. Instead, “this was a testament to the urgency,” Ms. Dworken said. “We are trying to do something, but we don’t have a plan or an infrastructure.” And, she noted, “this is all women-driven.”

Teaneck’s mayor, Mohammed Hameeduddin, was among the speakers, who also included, among many others, newly installed Rep. Josh Gottheimer (D-Dist. 5) and Rep. Frank Pallone (D-Dist. 6). “I think that President Trump is really taking advantage of people’s fears,” Mayor Hameeduddin said. “He is putting together some draconian policies, and hoping that people will not question him, and instead fall in line with those policies. It is very interesting to see the spontaneous reactions to it. Without any organization, when people heard that other people were being detained at the airports, they rushed there to help.

“You have an awakening of opposition as we see what is and what is not acceptable in the American experience. There is a lot of room for debate and disagreement about foreign or economic or domestic policy, but something that no one in America could accept is people taking away other people’s rights.”

As for the Muslim ban, Mr. Trump might have backed off that description of his decision to ban refugees from seven majority Muslim countries – although not such majority Muslim countries as Saudi Arabia, Pakistan, Egypt, and Turkey, where terrorism is rife but where Mr. Trump seems to have done or have wanted to do business – but his close campaign advisor, New York City’s former mayor, Rudolph Giuliani, explained that in fact Mr. Trump did see it as a ban on Muslims. “That is something that no one should accept in America,” Mayor Hameeduddin said.

But if there is any good in any of this, it is in the inclusiveness of the response to it, both nationally and locally, both Mayor Hameeduddin and Ms. Dworken said. “The women of Teaneck, particularly the women of Netivot Shalom and other synagogues, pushed this forward and made it happen,” the mayor said. “They inspired me. I can’t process it now, but it really was an amazing day. Teaneck is really special. That is who we are.”

Ms. Dworken agreed. The group that put together a rally is interfaith on purpose, but that is more of a side benefit to its main goal – figuring out how to oppose what it sees as dangerous policies – than its major intent. “We are moms,” she said. “Most of us also have full-time or part-time jobs, and a lot of responsibilities. We don’t have the intention of making this group something formal. We just want to see it grow.

“We don’t know what we will do next. We are not the ACLU. We do not have those resources. We would love to be able to direct people to those resources. We have to figure out the next step,”  Ms. Dworken said. She echoed Mayor Hameeduddin: “We are still processing it,” she said.