Nearly 150 professional investors are "strongly urging" gun makers, retailers and distributors and the companies that finance the gun industry to take action in response to gun violence.

The group includes dozens of faith-based organizations and U.S. and European asset management firms, many of them active in promoting social and environmental causes, collectively with $634 billion of investor assets under management.

In a statement circulated on Thursday, they are asking companies "to carefully reflect on how their operations, business relationships, supply chain policies, marketing practices and public voices might be used to counter gun violence and foster safer communities."

The group is being led by the Interfaith Center on Corporate Responsibility, which has been talking to gun makers and retailers for several years. Members have recently filed shareholder proposals at gun makers asking them to assess the risks of their business.

The group is asking the gun industry and those that support it to "review their operations, supply chains and policies and take meaningful action on this significant public safety concern."

Efforts to put an end to gun violence have gotten new momentum in the weeks since a deadly school shooting in Parkland, Florida, sparked national rallies led by students who survived that shooting and calls for new gun safety laws.

"The bravery and eloquence of the Parkland students has brought us to a tipping point on this issue," said Adam Kanzer, a managing director of Domini Impact Investments, who helped draft the statement. "Today, we are asking investors and corporations large and small to take a hard look at their connections to gun violence and do what they can to restore peace and safety to our communities. We hope that our recommendations will serve as a blueprint for these actions."

Some companies have already responded. Dick's Sporting Goods, Walmart, LL Bean and Kroger changed their policies regarding gun sales, and Citigroup imposed new restrictions on lending to retail clients involved in the gun business.

Several companies dropped loyalty reward programs they offered to members of the National Rifle Association, including car rental companies Hertz, Alamo and National; hotels Wyndham and Best Western, and airlines Delta and United.

And the world's largest asset manager, BlackRock, told clients in a letter earlier this month it was time to take a stand, saying it could use its position as one of the biggest owners of publicly traded gun makers to vote against directors or support shareholder proposals.

The group statement outlines steps gun makers, retailers and lenders can take. Gun makers, for example, should stop making and selling military-style semi-automatic weapons for civilians and support a federal universal background check system, the statement says.

In addition, the group asks that retailers stop selling guns and ammunition to people under age 21 (as some already have done) and stop selling realistic toy guns and air rifles. And it calls on banks to stop allowing credit cards to be used to buy guns and to stop lending to manufacturers that don't support federal universal background checks.

All companies are asked to end commercial relationships and promotional ties with the NRA and to consider moving corporate events to states that have "responsible gun legislation and that promote public safety," the statement says.

"ICCR members have a long history of addressing violence in our society through many, diverse corporate connections," said Mark Regier of Everence Financial/Praxis Mutual Funds. "Moving the conversation on gun violence beyond the manufacturers and retailers is a critical next step."