Use CSS Modules in React components with Typescript built by webpack

I want to use the css-loader with the 'modules' option of webpack in a React application written in Typescript. This example was my starting point (they are using Babel, webpack and React).

webpack config

var webpack=require('webpack');
var path=require('path');
var ExtractTextPlugin=require("extract-text-webpack-plugin");

module.exports={
    entry: ['./src/main.tsx'],
    output: {
        path: path.resolve(__dirname, "target"),
        publicPath: "/assets/",
        filename: 'bundle.js'
    },
    debug: true,
    devtool: 'eval-source-map',
    plugins: [
        new webpack.optimize.DedupePlugin(),
        new webpack.optimize.UglifyJsPlugin({minimize: true})
    ],
    resolve: {
        extensions: ['', '.jsx', '.ts', '.js', '.tsx', '.css', '.less']
    },
    module: {
        loaders: [
            {
                test: /\.ts$/,
                loader: 'ts-loader'
            },
            {
                test: /\.tsx$/,
                loader: 'react-hot!ts-loader'
            }, {
                test: /\.jsx$/,
                exclude: /(node_modules|bower_components)/,
                loader: "react-hot!babel-loader"
            },
            {
                test: /\.js$/,
                exclude: /(node_modules|bower_components)/,
                loader: "babel-loader"
            }, {
                test: /\.css/,
                exclude: /(node_modules|bower_components)/,
                loader: ExtractTextPlugin.extract('style-loader', 'css-loader?modules&importLoaders=1&localIdentName=[name]__[local]___[hash:base64:5]!postcss-loader')
            }
        ]
    },
    plugins: [
        new ExtractTextPlugin("styles.css", {allChunks: true})
    ],
    postcss: function() {
        return [require("postcss-cssnext")()]
    }
}

This is a React component I want to style with an accompanying CSS file:

import React = require('react');
import styles = require('../../../css/tree.css')

class Tree extends React.Component<{}, TreeState> {
...

    render() {
        var components = this.state.components
        return (
            <div>
                <h3 className={styles.h3} >Components</h3>
                <div id="tree" className="list-group">
                    ...
                </div>
            </div>
        )
    }
}

    export = Tree

tree.css

.h3{
    color: red;
}

No matter what I'm doing (tried changing the import syntax, tried declaring the 'require' for ts-loader, described here, I always get:

Uncaught Error: Cannot find module "../../../css/tree.css"

at runtime and

error TS2307: Cannot find module '../../../css/tree.css'.

by the TS compiler. Whats happening? Seems to me that css-loader is not even emitting ICSS? Or is it ts-loader behaving wrong?