SEATTLE -- Late afternoon thunderstorms and lightning strikes broke out along the Kitsap Peninsula west of Seattle and moved into the Seattle metro area, KIRO 7 Chief Meteorologist Rebecca Stevenson said.

The system, along with rain showers, developed in the Puget Sound convergence zone Monday afternoon and spread east through Seattle.

Thunder shook downtown Seattle during the early evening commute, while in SeaTac, gusty winds and heavy rains swept through the area and slowed traffic on Interstate 5.

Stevenson said funnel clouds could form during the storm along with small hail and warned people to stay indoors during the lightning strikes.

KIRO 7 storm chaser Billy Griffin said he saw a funnel cloud directly over the city of Renton at Interstate 405 and state Route 167 shortly after 5 p.m., then reported seeing a funnel cloud actually touch down for three to four minutes northeast of Black Diamond, which would classify it as a tornado, Griffin said.

Griffin said that ultimately, his video footage of the event would have to be reviewed by the National Weather Service to determine if it was indeed an actual tornado.

The last large tornado in the state hit Vancouver in January where a rowing club was destroyed and cut a swath four miles long.

Monday's storm also cut power to 900 people in Bremerton as heavy rain hit the area late Monday afternoon.

The activity is expected to decrease as the convergence zone moves into the Cascades overnight.

Earlier in the day, several people spotted a funnel cloud over Lake Washington , a sighting that National Weather Service forecasters acknowledged after seeing video shot by a KIRO 7 Eyewitness News viewer. The Weather Service said the video, shot by an Eastside resident, indicated it was a funnel cloud rather than the "fragmented clouds" forecasters first thought.

Stevenson told National Weather Service officials about the video.

"We were able to provide them a better look (at the funnel cloud)," she said, which they were otherwise unable to confirm.

The cloud spun in the sky over the lake at about 8:40 a.m.