CHAMONIX, France – More than 8,100 runners from around the world flooded into Chamonix on Aug. 28-Sept. 3 for the five ultramarathon races that make up the Ultra-Trail du Mont-Blanc endurance festival that bills itself as the World Summit of Trail-Running.

Included among the thousands of runners were seven from Massachusetts who took part in three of the races.

Five Bay State residents took part in the 101-kilometer CCC, while one raced the 56-kilometer OCC and one tackled the festival’s longest race, the 290-kilometer PTL.

No Massachusetts residents competed in the 105-mile UTMB or the 119-kilometer TDS.

The event’s shortest ultra – the 56-kilometer OCC – began under a steady rainfall on Thursday morning, Aug. 31, in Orsieres, Switzerland, with 1,565 runners taking to the course. After the race-specific unique starting route, runners quickly made their way to Champex-Lac where they connected into the main course. Their final 28 miles were the same as the UTMB and CCC courses. By the end of the rain-soaked day, OCC runners climbed around 11,000 feet before making their final descent into Chamonix.

Marc Lauenstein of Switzerland earned the victory in 5:19:34, four minutes ahead of runner-up Thibaut Baronian of France.

Chad Verry, 38, of Pembroke, Mass., was one of 24 Americans in the field, and he put together a steady performance. Verry got stronger as the race went on. Between Champex-Lac and the finish line he climbed nearly 150 places in the overall race field while placing 549^th overall in 9:36:28.

A day later, on Friday, Sept. 1, five Massachusetts residents were among the 2,155 runners who gathered at the starting line in Courmayeur, Italy, to begin their 63-mile, three country journey into Switzerland and ultimately back to France and the finish line in Chamonix while climbing around 20,000 feet along the way.

Early morning rain gave way to clear, sunny skies for the start of the CCC as Boston’s Palo Cvik, Belmont’s Damien and Meredith Pinault, and Medford’s Alex Brinkert and Chris Wristen wound through the crowded streets of Courmayeur and began the 4,700 foot climb up Tete de la Tronche.

Good weather remained through the downhill miles to Refuge Bertone and the rolling miles to Refuge Bonatti (22 KM) and Arnouvaz (27 KM). After that, the forecasted nasty conditions began to kick in.

Dark clouds billowed over the Grand Col Feret, the course’s second major climb and the entry point to Switzerland. Rain pelted the runners on their climb up, and a thick fog greeted them for the long descent down the other side. By the time they reached Champex-Lac (55 KM), a downpour fell and turned the course into a soupy mud for most of the remaining 28 miles.

Seventy-four Americans took part in CCC, and two of them brought home victories. Hayden Hawks of Utah earned the overall win in 10:24:30, while Colorado’s Clare Gallagher was the women’s champion in 12:13:57.

Three of the Massachusetts runners finished the race within its 26 1/2-hour time limit. Cvik made CCC the latest in a series of strong ultramarathon performances in 2017. After completing more than a half-dozen ultras as part of his preparation this year – most recently a top-five finish at the Under Armour Mountain Running Series 50K in Killington, Vt., two weeks before race day – the 31-year-old spent most of the CCC running in the top 20 percent of the field. He climbed as high as 203^rd place before fading a bit during the final 15 kilometers. Ultimately, Cvik returned to Chamonix and crossed the finish line at 2:19 a.m. in 296^th place overall after 17:18:29 of running.

Brinkert, 31, and Wristen, 37, also finished the race. Brinkert started in wave one and Wristen started 15 minutes in wave two. They connected 15 kilometers into the race at Refuge Bertone, and completed the final 54 miles together before finishing side by side. Wristen’s time was 25:40:51, and Brinkert’s finishing time was 25:55:17.

Damien Pinault, 45, and Meredith Pinault, 40, completed the race’s first major climb over Tete de la Tronche, but both dropped from the race at Arnouvaz after 27 kilometers and nearly six hours on the course.

Dima Feinhaus had the longest time on the trail of any of the Massachusetts runners. The 54-year-old Waban resident was one of four Americans who took part in the 290-kilometer PTL, a continuous multi-day team event that winds through France, Italy and Switzerland and pounds runners with numerous major climbs totaling more than 85,000 feet of gain.

Feinhaus and teammate Laurent Theze of France were one of 61 teams to finish within the 151-hour, 30-minute time limit. They departed Chamonix under cloudy skies but with dry conditions on Monday morning, Aug. 28. After more than five days in the mountains, during which time they had some ideal weather but also battled rain and snow, they returned to downtown Chamonix and crossed the finish line at 3:31 a.m. Sunday. Feinhaus and Theze placed 24^th overall in 138:31:32.

Nicolas Lehmann of Switzerland and Nicolas Cerisier of France teamed to win the PTL in 1:17:27:09, nearly nine hours faster than the second-place team.