Aspen Insurance Holdings Ltd.’s third-quarter 2015 earnings fell amid $50 million in losses caused by the August explosion in the port of Tianjin, China, and natural catastrophes in other regions of the world, according to the company.

The Hamilton, Bermuda-based insurer and reinsurer experienced a 24.6% decrease in net income to $28.2 million in the third quarter of 2015 compared with the same period last year, the company stated in its third-quarter earnings report released on Monday. The company’s operating income also declined 17.7% to $67.2 million from the third quarter of 2014, according to the report.

Overall, gross written premiums increased by 10.4% to $720.5 million in the third quarter of 2015 compared with the third quarter of 2014, according to the report. But underlying revenue declined amid $50 million in total losses related to the Tianjin explosion and natural catastrophes, namely wildfires in Washington state and an earthquake in Chile, according to company officials.

The overall combined ratio was 93.4% for the third quarter of 2015 compared with 94.6% for the third quarter of 2014, according to the company.

For the nine-month period, net income declined 28.9% to $205.2 million compared with the same period of 2014, while operating income fell 20.1% to $237.4 million, according to the release.

For the insurance segment, gross written premiums totaled $403.9 million, an increase of 2.1% compared with the third quarter of 2014, with the United States and international businesses contributing significantly to underwriting performance even though overall rates in both segments were down 1% and 2%, respectively, Chris O’Kane, Aspen’s CEO, said during the company’s third-quarter earnings conference call Tuesday.

“Our insurance business had a very strong quarter,” he said. “We continue to operate in a rate environment that poses some challenges. There was significant variation by lines of business, with some areas under continued pressure while others were steady.”

Gross written premiums rose 23.2% to $316.6 million in the reinsurance segment in the third quarter of 2015, according to company officials.

“While the reinsurance rate environment remains soft, with overall rates down 6% on average, we see some encouraging signs that the pace of rate reduction is slowing, and market discipline is building,” Mr. O’Kane said.

The company reported $10.6 million in other expenses in the quarter primarily related to Silverton Re, its Bermuda-domiciled special purpose insurer, which was established in December 2013 to provide additional collateralized capacity to support Aspen Re’s global reinsurance business. The third-quarter expenses reflect the amount due to third-party investors in the sidecar, Aspen Chief Financial Officer Scott Kirk said during the conference call.

“This amount reflects a relatively benign cat experience for Silverton Re this quarter,” he said.