The low inventory of homes for sale is making life more difficult for some real estate agents, and in some markets there are twice as many real estate professionals as there are available listings.

That means agents are fighting among themselves to get in on the sales action, and some are resorting to desperate measures to find more housing choices for their prospective clients.

“This is not the time for amateurs,” said Dana Bull, a Boston-based real estate agent, in an interview with CNBC. “This is the big leagues here.”

With the inventory of home for sale so tight, bidding wars have become very common in some markets. The latest Realtor Confidence Index shows there were 20% fewer homes listed for sale in March than there were in the same month one year ago. National Association of Realtors’ affiliated agents say they receive an average of four offers on each home they sell.

Bull told CNCB she is “pulling out all the stops” to try and drum up more business, getting heavy on social media and sending out emails to prospective buyers and sellers.

“We are tapping our network, trying to facilitate some of these transactions, and some of them are happening, going into Boston, out of Boston, out of state, across the country,” she said. “We are networking and doing everything we can, working our channels and working our connections.”

Others are taking an even more direct approach. Ryan Waller, an agent with Home Group Realty in Ontario, told Money.com that when one of his clients cannot find a suitable home, he goes with them on a stroll around their chosen neighborhood to try and find homes that might interest them. Then, he helps his clients to draft a letter to the owners of those homes to see if they might consider selling. It’s an unusual tactic that has had good results, he said.

Waller said that some homeowners have ended up agreeing to sell their homes because they weren’t aware of just home much their home’s value has appreciated over the last year. When they realize how much money they can make from selling, and that a buyer is already interested, many go ahead and cash in, he said.

In addition, Waller said he has also turned to local media to try and get the message out that now is a great time to sell.

“We’re big marketers in town and have also resorted to the media to help us—running ads on local radio stations with messages like ‘We have buyers looking for the following…,” he said. In his ads, he even mentions specific neighborhoods and the types of homes his clients are interested in, such as the number of bedrooms and other details they want, to try and convince homeowners to contact him. He runs similar ads in local newspapers too, he said.

Another tactic that some agents are using to try and find more listings is to follow divorce announcements, obituaries and foreclosure notices, CNBC reported. If they learn about a divorce for example, they will call the homeowners to ask about what they are planning to do with the property. They pitch the benefits of selling and some have even made cash offers on the spot, CNBC said.

The big problem of course is that many homeowners will be concerned that the lack of homes for sale means that if they do sell, they won’t have anywhere to move to. So, agents have to be ready to entice them by showing them the available listings they do have, Bull said.

“It kind of feels like a game of Tetris,” Bull told CNBC, She said that she has to look at “the whole playing board, and we’re trying to place people and strategically move people around in a way that best fits their lifestyle.”